"barchart" 5580, 2445, 6735, 2745 4470, 3450, 6735, 3750 "HM5" "HM1" "HM2" "HM4" "HM12" "HM22" "HM42" "HM52" "HM11" "HM21" "HM31" "HM41" "HM51" "text1" "text2" "text3" "text4" "text5" "text6" "text7" "text8" "text9" "In order fully understand illustration:"\ && "Study the effect BPG concentration )one particular oxygen tension"\ && " 4changing && "For example, study )concentrations 10mM cpartial pressure 100mmHg."\ && "Once you have grasped concept, change --situation where "2"=4470 "1"=4470 "1"=5580 "2"=5760 "1"=5580 "2"=6225 "1"=4470 "2"=4470 "1"=4470 "2"=5760 "1"=4470 "2"=6225 yension "1"=6720 "2"=4470 "1"=6720 "2"=5760 "1"=6720 "2"=6225 5580, 2445, 6735, 2745 4470, 3450, 6735, 3750 terPage enterPage leavePage enterPage barchart barchart text1 text2 text3 text4 text5 text6 text7 text8 text9 In order to fully understand this illustration: Study the effect of changes in BPG concentration at one particular oxygen tension before changing the oxygen tension. For example, study the effect of BPG at concentrations of 5mM and 10mM at a oxygen partial pressure of 100mmHg. Once you have grasped this concept, change the oxygen tension and continue the study as before. text1 text2 text3 text4 text5 text6 text7 text8 text9 text4 text1 text2 text3 text5 text6 text7 text8 text9 text7 text4 text1 text2 text3 text5 text6 text8 text9 text2 text1 text3 text4 text5 text6 text7 text8 text9 text5 text4 text1 text2 text3 text6 text7 text8 text9 text8 text4 text1 text2 text3 text6 text7 text9 text3 text2 text1 text4 text5 text6 text7 text8 text9 text6 text5 text4 text3 text2 text1 text7 text8 text9 text9 text5 text4 text3 text2 text1 text7 text8 leavePage barchart barchart text1 text2 text3 text4 text5 text6 text7 text8 text9 ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page :PHYSSIZE NextPage default buttonUp buttonUp default backPage Previous default buttonUp buttonUp Previous default The model shows the four subunit structure of haemoglobin with the haem groups (gold) and iron atom (silver). Try videos on next page 4drop "HM3" "HM2" "HM1" "HM11" "O21" 3880, 2660 3880, 2660, 4300, 2975 "O22" 4690, 2660 4690, 2660, 5125, 2975 3880, 2660 4690, 2660 3940, 2660, 4250, 2975 3880, 2660, 4300, 2975 3940, 2660, 4250, 2975 nthe 3170, 2660 3170, 2660, 3590, 2975 ZhorizPos 3170 -370 H-100 ., 2660 3880, 2660 3880, 2660, 4300, 2975 4750, 2660, 5075, 2975 4690, 2660, 5125, 2975 4750, 2660, 5075, 2975 5580, 2660 5580, 2660, 6015, 2975 5580 8980 , 2660 4690, 2660 4690, 2660, 5125, 2975 enterPage enterPage 333333 horizPos:by horizPos:to horizPos "quest5" "quest6" leavePage leavePage quest5 quest6 6. How many types of subunit does Haemoglobin contain?:::::::::::::::::: 6eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 5. Is Haemoglobin:::::::::::::::::::::: A monomer A dimer A trimer A tetramer A pentamer quest5 quest6 NextPage 4questscore5 4questscore6 B"5a" B"5b" B"5c" B"5d" B"5e" B"6a" B"6b" B"6c" B"6d" B"6e" default buttonUp buttonUp default questscore6 questscore5 "quest7" "quest8" leavePage leavePage quest7 quest8 7. What atom is found in the centre of a Haem molecule? Calcium Sodium Sulphur Phosphorus 8. Which subunit contact is altered in the R-T state transition? a1/b1 a2/b2 a1/b2 a2/b1 a1/a2 quest7 quest8 Basic NextPage 4questscore9 4questscore10 B"9a" B"9b" B"9c" B"9d" B"9e" B"10a" B"10b" B"10c" B"10d" B"10e" default buttonUp buttonUp default questscore10 questscore9 "quest9" "quest10" leavePage leavePage quest9 quest10 9. How many electrostatic interactions stabilize the T state? 10. The shape of the haemoglobin-oxygen dissociation curve is:::G Hyperbolic Linear Convex Sigmoidal Concave quest9 quest10 Basic NextPage 4questscore11 4questscore12 B"11a" B"11b" H1.25 B"11c" H1.25 B"11d" H1.25 B"11e" H1.25 B"12a" B"12b" B"12c" B"12d" B"12e" default buttonUp buttonUp default questscore12 questscore11 "quest11" "quest12" leavePage leavePage quest11 quest12 11.Which statements are correct concerning oxygen binding to haemoglobin? The binding of the 1st oxygen is the least difficult The binding of the 2nd oxygen is easier than the 1st The binding of the 3rd oxygen is easier than the 2nd The binding of the 4th oxygen is easier than the 3rd The binding of the 4th oxygen is easier than the second 12. Which statements about the T and R states of haemoglobin are true? Deoxyhaemoglobin is in the R state Oxyhaemoglobin is in the R state R stands for the 'ready' state T stands for the 'tense' state Oxygen binding promotes conversion to the T stateggggggggg quest11 quest12 Basic "quest13" "quest14" leavePage leavePage quest13 quest14 14. What effect does BPG have on Haemoglobin?::::::::::::::::::::::: Increases the affinity for oxygen Decreases the affinity for oxygen High levels of BPG increase oxygen delivery Stabilizes the T state Stabilizes the R state quest13 quest14 13. Does BPG interact with:::::::::: Both the T and R states of haemoglobin Haemoglobin in the T state Haemoglobin in the R state Haemoglobin at a ratio of one BPG/molecule Haemoglobin at a ratio of one BPG/subunittyyyany way any wayn any way NextPage 4questscore13 4questscore14 B"13a" B"13b" B"13c" B"13d" B"13e" B"14a" B"14b" B"14c" B"14d" B"14e" default buttonUp buttonUp default questscore14 questscore13 4questscore19 4questscore20 B"19a" B"19b" B"19c" B"19d" B"19e" B"20a" B"20b" B"20c" B"20d" B"20e" 4questscore18 4questscore17 4questscore16 4questscore15 4questscore14 4questscore13 4questscore12 4questscore11 4questscore10 4questscore9 4questscore8 4questscore7 4questscore6 4questscore5 4questscore4 4questscore3 --System count questscores --Obtain dialog box showing total no points "You scored" && out a possible 100" --shows nextpage B- avoids Bbeing pressed without --obtaining B"NextPage" default buttonUp buttonUp You scored points out of a possible 100 NextPage default count questscore1 questscore2 questscore3 questscore4 questscore5 questscore6 questscore7 questscore8 questscore9 questscore10 questscore11 questscore12 questscore13 questscore14 questscore15 questscore16 questscore17 questscore18 questscore20 questscore19 Basic NextPage 4questscore17 4questscore18 B"17a" H1.25 B"17b" B"17c" H1.25 B"17d" H1.25 B"17e" H1.25 B"18a" B"18b" B"18c" B"18d" B"18e" default buttonUp buttonUp default questscore18 questscore17 "quest17" "quest18" leavePage leavePage quest17 quest18 quest17 quest18 17. Which of the following happens in actively working tissues?HH Carbon dioxide reacts with water The pH increases The hydrogen ion concentration increases The affinity of haemoglobin for oxygen is decreased Hydrogen ions combine with haemoglobin 18. What effect does a lower pH value(e.g pH 7.2) have on haemoglobin?:::::::: Shifts the T-R equilibrium in favour of the T state Shifts the T-R equilibrium in favour of the R state Causes protonation of a histidine residue Causes deprotonation of a histidine residue Decreases the amount of oxygen unloaded in the tissues Basic B"NextPage" "quest19" "quest20" enterPage leavePage enterPage NextPage leavePage quest19 quest20 NextPage 4questscore19 4questscore20 buttonUp buttonUp questscore20 questscore19 quest19 quest20 20. What effect does carbon dioxide have on Haemoglobin?::::::::is :: 19. In which form is carbon dioxide transported by haemoglobin?:::::::::::::::: As bicarbonate As carbon dioxide As carbon monoxide As carbamate Is not transported by haemoglobinn Score Press the 'Score' button after finshing the questions to obtain your final score. No effect Increases the affinity for oxygen Decreases the affinity for oxygen Stabilizes the T state Stabilizes the R state B"NextPage" 4questscore20 4questscore19 4questscore18 4questscore17 4questscore16 4questscore15 4questscore14 4questscore13 4questscore12 4questscore11 4questscore10 4questscore9 4questscore8 4questscore7 4questscore6 4questscore5 4questscore4 4questscore3 4count -- If the a question < 5, i.e got something wrong, -- answer that shown. "answer1" "answer2" "answer3" "answer4" "answer5" "answer6" "answer7" "answer8" "answer9" "answer10" "answer11" "answer12" "answer13" "answer14" "answer15" "answer16" "answer17" "answer18" "answer19" "answer20" enterPage leavePage enterPage NextPage answer1 answer1 answer2 answer2 answer3 answer3 answer4 answer4 answer5 answer5 answer6 answer6 answer7 answer7 answer8 answer8 answer9 answer9 answer10 answer10 answer11 answer11 answer12 answer12 answer13 answer13 answer14 answer14 answer15 answer15 answer16 answer16 answer17 answer17 answer18 answer18 answer19 answer19 answer20 answer20 NextPage count questscore1 questscore2 questscore3 questscore4 questscore5 questscore6 questscore7 questscore8 questscore9 questscore10 questscore11 questscore12 questscore13 questscore14 questscore15 questscore16 questscore17 questscore18 questscore19 questscore20 leavePage answer1 answer2 answer3 answer4 answer5 answer6 answer7 answer8 answer9 answer10 answer11 answer12 answer13 answer14 answer15 answer16 answer17 answer18 answer19 answer20 count questscore1 questscore2 questscore3 questscore4 questscore5 questscore6 questscore7 questscore8 questscore9 questscore10 questscore11 questscore12 questscore13 questscore14 questscore15 questscore16 questscore17 questscore18 questscore19 questscore20 Basic B3<3<3 .b0:1 answer1 "answer1" buttonUp buttonUp answer1 Question 1: A single red blood cell is capable of carrying 200 million molecules of oxygen. and lactose transacetylase - i.e those that control the entry and metabolism of lactose. "answer1" buttonUp buttonUp answer1 answer20 "answer20" buttonUp buttonUp answer20 Question 20: Carbon dioxide decreases the affinity of haemoglobin for oxygen by stabilizing the T state. ese symmetrical sites are involved in the binding of the repressor and CAP-cAMP complex to the repressor site and CAP site respectively.to the DNA. answer19 "answer19" buttonUp buttonUp answer19 Question 19: Carbon dioxide combines with unprotonated a-amino groups in both subunits of haemoglobin as a carbamate.h subunit of the CAP. inding of the appropriate molecule to the DNA strand. answer18 "answer18" buttonUp buttonUp answer18 Question 18: Hydrogen ions promote the R to T transition by protonation of Histidine 146 in the b globin. This results in increased oxygen delivery to working tissues. rator. the DNA strand. answer17 "answer17" buttonUp buttonUp answer17 Question 17: In actively working tissues carbon dioxide forms carbonic acid in water and therefore the pH drops and the hydrogen ion concentration rises. The affinity of haemoglobin for oxygen is reduced as hydrogen ions combine with haemoglobin promoting the R to T transition. answer16 "answer16" buttonUp buttonUp answer16 Question 16: Histidine 146 binds a hydrogen ion in the T to R transition and is thus involved in the Bohr effect.nd galactose. Both these molecules can be used for energy and as a carbon source. answer15 "answer15" buttonUp buttonUp answer15 Question 15: At 4500m less oxygen is taken up by haemoglobin in the lungs and the BPG concentration in the red cell increases. This leads to a decrease in the affinity of haemoglobin for oxygen and the net effect is that oxygen delivery remains the same. answer14 "answer14" buttonUp buttonUp answer14 Question 14: BPG decreases the affinity of haemoglobin for oxygen, stabilizing the T state. High levels of BPG lead to enhanced ability to deliver oxygen to working tissues.d as a carbon source. answer13 "answer13" buttonUp buttonUp answer13 Question 13: BPG binds to the central cavity in the T state of haemoglobin and only one molecule binds to each haemoglobin molecule........None of the others can directly induce transcription. answer12 "answer12" buttonUp buttonUp answer12 Question 12: Deoxyhaemoglobin is usually in the T state with oxyhaemoglobin in the R state. R stands for Relaxed and T stands for tense. Oxygen binding promotes the T to R transition. ion. answer11 "answer11" buttonUp buttonUp answer11 Question 11: The binding of the first oxygen to haemoglobin is the most difficult and the binding of subsequent oxygens gets progressively easier.i.e. Oxygen binding to haemoglobin is cooperative. answer10 "answer10" buttonUp buttonUp answer10 Question 10: The slope of the haemoglobin-oxygen dissociation curve is sigmoidal....these conditions the CAP-cAMP complex is formed. The binding of this complex to the CAP site increases transcription by interacting with the RNA polymerase or by forming a bend in the DNA.nteracting with the RNA polymerase or by forming a bend in the DNA.by forming a bend in the DNA. answer9 "answer9" buttonUp buttonUp answer9 Question 9: Eight electrostatic interactions stabilize the T state. All eight electrostatic bonds involve the C- terminal amino acid residues of either the a or b subunits.e promoter by 100 fold. The result of this is that when lactose enters the cell the RNA polymerase is ready to start transcription immediately, leading to very quick production of the proteins. answer8 "answer8" buttonUp buttonUp answer8 Question 8: The a1/b2 and a2/b1 contacts are altered in the transition from T to R state.....ucose concentration has no effect on the lactose concentration or the allolactose concentration. on or the allolactose concentration. enters the cell the RNA polymerase is ready to start transcription immediately, leading to very quick production of the proteins. answer7 "answer7" buttonUp buttonUp answer7 Question 7: Haem has a Fe(II) atom chelated at its centre..... transcription. In the absence of cyclic AMP the CAP cannot bind to the CAP site so the promoter remains relatively inefficient. Thus only small amounts of permease made leading to low lactose uptake into the cell. is made so only a small amount of lactose enters the cell. uction of the proteins. answer6 "answer6" buttonUp buttonUp answer6 Question 6: There are two types of subunit a globin and b globin.....It is the complex between the two that can bind to the CAP site. ecient. It also leads to the reduced entry of lactose because only a small amount of permease is made so only a small amount of lactose enters the cell. ion immediately, leading to very quick production of the proteins. answer5 "answer5" buttonUp buttonUp answer5 Question 5: Haemoglobin is a tetramer with 4 subuints, 2 a globins and 2 b globins. ds to the reduced entry of lactose because only a small amount of permease is made so only a small amount of lactose enters the cell. ion immediately, leading to very quick production of the proteins. answer4 "answer4" buttonUp buttonUp answer4 Question 4: Haemoglobin is unusually rich in a helices and contains very little pleated sheet. In this respect it is a typical protein. Haem is hydrophobic and is held in a hydrophobic pocket. One BPG molecule binds in the centre of haemoglobin which is an archetypal allosteric protein. ll. ion immediately, leading to very quick production of the proteins. answer3 "answer3" buttonUp buttonUp answer3 Question 3: In normal working tissues the amount of oxygen unloaded by a single red cell is 80% but this could vary somewhat depending upon the exact circumstances. lactose because only a small amount of permease is made so only a small amount of lactose enters the cell. ion immediately, leading to very quick production of the proteins. answer2 "answer2" buttonUp buttonUp answer2 Question 2: The concentration of oxygen in blood is 0.01M 100 x greater than in plasma (0.0001M). The concentration of oxygen in the red cell is 200 x that in plasma. nly a small amount of permease is made so only a small amount of lactose enters the cell. ion immediately, leading to very quick production of the proteins. The answers to the problems that you got wrong can be seen below. Once you have read the correct answer click the mouse in the white box to move onto the next answer. Answers to Haemoglobin Questions NextPage default buttonUp buttonUp default ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page answer 1st Page "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage ExitProgram buttonUp buttonUp The Effect of BPG on the T to R State Equilibriumnnn The effect of BPG on haemoglobin depends, to some extent, on the partial pressure of oxygen. In the lungs (pO =100mmHg), 5mM of BPG is incapable of altering the T to R state equilibrium significantly, therefore haemoglobin is found to be all in the R state and fully oxygenated. A BPG concentration of 10mM also has no effect. In working tissue (pO = 40mmHg), BPG shifts the equilibrium towards the T state causing haemoglobin to unload most of its bound oxygen.The higher the BPG concentration the greater the shift towards the T state. In highly active tissue (pO = 20mmHg), BPG shifts the equilibrium further towards the T state. This allows haemoglobin to unload almost all its bound oxygen........................................................a o The following page illustrates the above.nds to the T state of haemoglobin........nnnnn.. ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Aims and Objectives Introduction This program is intended for use by students in their first or second year taking Biochemistry as part of their course. The program makes use of animations to illustrate the dynamic aspects of the structure and functions of Haemoglobin. The aims and objectives are as follows: 1. To illustrate the structural features of haemoglobin. 2. To illustrate the binding properties of haemoglobin for oxygen and how these determine its ability to deliver oxygen to working tissues. 3. To illustrate the influence of hydrogen ions and 2,3-BPG on the ability of haemoglobin to bind and deliver oxygen to working tissues. 4. To test your understanding of the tutorial by means of a multiple-choice quiz.hoice quiz.tanding of the tutorial by means of a multiple-choice quiz.rstanding of the tutorial by means of a multiple-choice quiz. ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The Effect of Carbon Dioxide on Oxygen Affinityyy In aerobic metabolism about 0.8 molecules of CO are formed per O molecule consumed. Most of the CO in the blood is carried in the form of bicarbonate, which is formed in red cells by the action of carbonic anhydrase.................................................................................................................................. ~ n " Much of the H generated by this reaction is taken up by deoxyhaemoglobin as part of the Bohr effect. The CO is carried by haemoglobin in the form of carbamate. The bound carbamates form salt bridges that stabilize the T state. Hence, the binding of carbon dioxide lowers the oxygen affinity of haemoglobin. cells by the action of carbonic anhydrase. Carbamate ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page "mplayer.exe b:\hb-jmb.avi" buttonUp buttonUp mplayer.exe b:\hb-jmb.avi T-R transition To access the video: 1. Press the "T-R Transition" or "Subunit" buttons below. 2. The Media Player (above) & Haemoglobin/Subunit molecule will be displayed. 3. To play the video, simply click the "Play" button. 4. To stop the video, click the "Stop" button. 5. To exit the Media Player, select the "File" menu and select "Exit". :PHYSSIZE :PHYSSIZE OTHERWISE IT COULDN'T BE SIMPLER !! PLEASE DO NOT TOUCH ANY OTHER BUTTONS OR MENUS. guide :PHYSSIZE Button "mplayer.exe b:\haem2.avi" buttonUp buttonUp mplayer.exe b:\haem2.avi Subunit "a1b1" "a2b2" "a1b2" "a2b1" enterPage leavePage enterPage leavePage ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The R State....... "a1b2" mouseenter mouseleave mouseenter mouseleave "a2b1" mouseenter mouseleave mouseenter mouseleave "a1b1" mouseenter mouseleave mouseenter mouseleave alpha1 beta1 "a2b2" mouseenter mouseleave mouseenter mouseleave beta2 alpha2 The subunits of the R state are held together by hydrophobic interactions. The major interactions involve approx. 35 amino acids and link the a to the b subunits. These are known as the a1/b1 interactions and are identical to the a2/b2 contact areas. These bonds stabilize the basic a/b dimer.Two dimers are linked to form the tetramer by smaller hydrophobic interactions that involve approx. 19 amino acids and are referred to as the a1/b2 and the identical a2/b1 contacts.............................................11 a1/b1 contactt a2/b2 contactt a1/b2 contactt a2/b1 contactt Move the cursor over the subunit contacts to display their identity. Summary Introductionnnnnn ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page 1. Haemoglobin is the major oxygen carrier in blood 2. Haemoglobin has four subunits and is an allosteric protein 3. Haemoglobin can exist in two conformational states - R and T 4. Oxygen binds to haemoglobin in a cooperative manner 5. Oxygen binding promotes formation of the R state 6. H ions, 2,3-BPG and CO all bind to haemoglobin in the T state and in doing so promote the R to T transition and thus the release of oxygen 7. The physiological consequences of these effects are illustrateddddd As ca Basic NextPage default buttonUp buttonUp default backPage Previous default buttonUp buttonUp Previous default ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page > Q U animation illustrates the effect high altitudes on percentage --oxygen released >tissues. sysCurosr shows d increasing sea level(0) 4500m "4500m" "Matterhorn" "Nanda Devi" "Everest" "Ap45" "Ap75" "Ap90" "VO2" "VO21" "VO290" default compensatory result increased BPG concentration erythrocytes =4500m "sea" 4500m 7500m levels "7500m" 7500m 9000m "9000m" adaptation (9000m) decrease venous pO2 buttonUp buttonUp 4500m altitude Matterhorn Nanda Devi Everest VO290 Matterhorn Nanda Devi Everest VO290 7500m altitude Nanda Devi Everest Matterhorn VO290 9000m altitude Everest Nanda Devi Matterhorn VO290 Everest Nanda Devi Matterhorn VO290 altitude Everest Nanda Devi Matterhorn VO290 default sysCurosr animation illustrates the release oxygen d blood cell tissues. "rp1" -2370, 1980 "text1" "text2" "textGo" H1500, 400 H1500, -400 H1500, 400 H1500, -400 Ungroup 4110, 765 4605, 630 3510, 675 4530, 975 3885, 1005 5070, 750 3240, 825 5625, 540 "81" "71" "rp2" H1500, 400 H1500, -400 H1500, 400 H550, 0 3630, 1980 4770, 2470 4545, 2040 4400, 2555 3885, 2640 3950, 2005 3660, 2090 3655, 2380 4060, 2010 Group -2370, 1980 default buttonUp buttonUp text1 text2 textGo WUngroup text2 text1 textGo text2 Group default This section contains 20 questions based on the information in the previous pages which will take about 10 minutes to complete. Once in the quiz it is only possible to go forwards - it is not possible to exit or return to previous pages. N.B. For each question there are 5 checkboxes. The correct answer may involve the checking of any number of boxes from 0 to 5. GOOD LUCK! Questions Basic Basic NextPage --see --questscore1 question 1. It zero Fincreases decreases depending on which answer boxes are --same applies questscores 2-20 --All forthcoming fquestions on have Jlayout except 4questscore2 B"1a" B"1b" B"1c" B"1d" B"1e" B"2a" B"2b" B"2c" B"2d" B"2e" default buttonUp buttonUp default questscore2 questscore1 --removes cross the answer boxes "quest1" "quest2" leavePage leavePage quest1 quest2 quest1 quest2 1. How much oxygen can a single red blood cell potentially carry ? 5 million molecules 100 million molecules 200 million molecules 1000 million molecules 2000 million molecules 2. The oxygen concentration in blood is: 100 x the concentration in plasma 200 x the concentration in plasma 10 M 10 M 10 MM Basic "quest3" "quest4" leavePage leavePage quest3 quest4 quest3 quest4 3. What percentage of oxygen is unloaded by a red blood cell in actively-working tissues? Select one value. actose 4. Haemoglobin ::::::::::: working tissues has the following effects:of oxygen unloaded: of oxygen unloaded:of oxygen unloaded: Has a high alpha helix content Has a hydrophilic binding pocket for haem Has a low beta pleated sheet content Is an allosteric protein Has four binding sites for BPG NextPage 4questscore3 4questscore4 B"3a" B"3b" B"3c" B"3d" B"3e" B"4a" B"4b" B"4c" B"4d" B"4e" default buttonUp buttonUp default questscore4 questscore3 Basic NextPage 4questscore7 4questscore8 B"7a" B"7b" B"7c" B"7d" B"7e" B"8a" B"8b" B"8c" B"8d" B"8e" default buttonUp buttonUp default questscore8 questscore7 illustration1 illustration2 illustration3 BPG & altitude ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The Effect of BPG on Oxygen Binding in BPG ( 2,3-Bisphosphoglycerate) binds to haemoglobin and has a large effect on its affinity for oxygen. This anionic organic phosphate is present in human red cells at about the same molar concentration as haemoglobin. BPG binds specifically to the T state of haemoglobin in a 1:1 ratio. It binds within the central cavity of a haemoglobin molecule and interacts between the two b subunits. On oxygenation, when the molecule shifts to the R state, the BPG is extruded because the central cavity becomes too small. BPG opposes this shift to the R state and thus decreases the oxygen affinity by stabilizing the the T state. Increases in BPG concentration decrease the oxygen affinity further................... "textGo" "text1" "rp1" 3050, 2350 "rp2" -1210, 2425 "rp3" -5890, 2405 "O2" 5025, 2115 "plasma" 4785, 2340, 5510, 2795 "plasma2" 4875, 1815, 5855, 2475 cell" 2790, 2055, 3765, 2745 cell2" "box1" "box2" "key" "text2" "text3" enterPage enterPage textGo text1 plasma plasma2 red cell plasma plasma2 red cell red cell2 text2 text3 /z0j1 cell1 animation1 Animate Press the "Animate" button. rbc12 rbc13 rbc11 *$Q"v rbc13 red cell plasma plasma2 Plasma --- represents 5,000,000 oxygen moleculessssssssssssss textGo REPEAT ANIMATION OR MOVE TO THE NEXT PAGEEE text3 In comparison a single red blood cell can carry 1000 million oxygen molecules i.e approx. 200 times more than the same volume of plasma can carry... text2 A volume of plasma equivalent to the volume of a red blood cell carries approximately 5 million oxygen molecules.......... (1x10 l)) text1 This animation illustrates the differences in the amount of oxygen carried by plasma and red blood cells. LO9 l $YA i red cell2 D@3 7 ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page 1.Stryer. L . Biochemistry (Third Edition). Published 1988. Pages 143-176. 2.Voet.D & Voet.J.G. Biochemistry. Published 1990. Pages 210-244. 3. Jones.J.G. The structure and function of Human Haemoglobin. (Handout)........................... Bibliography Introduction rX(F(F( "a1b1" "a2b2" "a1b2" "a2b1" "a1a2" enterPage leavePage enterPage leavePage ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The T State....... The same a1/b1 contacts are found in the T state as they are not altered by oxygen binding. The a1/b2 contact in the T state is altered however; being shifted in position. This relative movement of the two dimers is primarily stabilized by eight extra electrostatic bonds that are only found in the T state. All eight electrostatic bonds involve the C- terminal amino acids of either the a or b subunits. The narrower lines represent electrostatic interactions between a1/a2 (4), a1/b2, a2/b1 and intra b bonds (2). mouseenter mouseleave mouseenter mouseleave mouseenter mouseleave mouseenter mouseleave "a1a2" mouseenter mouseleave mouseenter mouseleave "ea2b1" mouseenter mouseleave mouseenter ea2b1 mouseleave ea2b1 "ea2b1" mouseenter mouseleave mouseenter ea2b1 mouseleave ea2b1 "a2b1" mouseenter mouseleave mouseenter mouseleave "ea1b2" mouseenter mouseleave mouseenter ea1b2 mouseleave ea1b2 "ea1b2" "ea2b1" mouseenter mouseleave mouseenter ea1b2 mouseleave ea2b1 "a1b2" mouseenter mouseleave mouseenter mouseleave "a1b1" mouseenter mouseleave mouseenter mouseleave "a1b1" mouseenter mouseleave mouseenter mouseleave "a2b2" mouseenter mouseleave mouseenter mouseleave "a2b2" mouseenter mouseleave mouseenter mouseleave beta2 t!j!q! a1/b1 contactt a2/b2 contactt f#>#c# a1/b2 contactt a2/b1 contactt Intra b2 bond Intra b1 bond ea1b2 Electrostatic a1/b2 bond bond ea2b1 Electrostatic a2/b1 bond bond x'0'u' Electrostatic a1/a2 bonds Move the cursor over the subunit contacts to display their identity. Structure of Haemoglobinnnnnnn ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Haemoglobin is a tetrameric protein composed of two pairs of identical subunits. In human adult haemoglobin these are the a and b subunits. The a subunit contains 141 amino acid residues and the b subunit contains 146 residues. Each subunit carries a haem molecule which is responsible for the binding of oxygen. There are two main conformational states of haemoglobin. In the absence of oxygen the T state predominates. When this binds oxygen a new conformation is generated, the R state. If this happens in the crystal state the crystal cracks indicating that a change in conformation has occurred. "rp1" -2370, 1980 "text1" "text2" "textGo" enterPage enterPage text1 text2 textGo z0>244 7x:n<2> A~CBE K|M@O cell1 Press the "Animate" button. Animation2 Animate Active Tissue (e.g Muscle ) S b%/ T l*M 6KJ ] text1 On reaching the capillaries in working tissues the red blood cell unloads around 80% of the oxygen it carries which diffuses into the surrounding tissues. textGo REPEAT ANIMATION OR MOVE TO THE NEXT PAGEEE text2 text2 The release of oxygen is promoted by the low [O ] in working tissues, the lower pH and the high [CO ]....VE TO THE NEXT PAGE "textGo" "text1" "HMr" "O21" 3595, 1895 "O22" 4570, 1895 "HMt" "HMh1" "HMh2" "HMh3" "HM1" enterPage enterPage textGo text1 4't( +,-l. 3$5l6 7>8v9@;P< T state R statee Animation5 Animate Press the "Animate" button... textGo REPEAT ANIMATION OR MOVE TO THE NEXT PAGEEE text3 Once two H ions are bound haemoglobin is able to change conformation to the T state.. text2 Approximately 3 H ions interact with haemoglobin. On interaction of the first H ion, the subunit attempts to snap the molecule to the T state but fails.. text1 The presence of higher levels of protons in capillaries of active tissue (e.g contracting muscle) promotes the release of oxygen from oxyhaemoglobin. text4 The interaction of the third H ion will lock the molecule into the T state and promote the unloading of O from the molecule. One or possibly both O 's may leave...... The Effect of Protons on the Oxygen Affinityyynnnnnnnnnnnnn Oxygenated Deoxygenated ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Binding of Oxygen by Haemoglobin.ggggggggggggggggggggggg The binding of oxygen to the T state of haemoglobin involves large conformational changes. Oxygenation causes the Fe atom to move into the plane of the haem 'pulling' the proximal histidine with it. This motion initiates the conformational change from the T state to the R state. This conformational change is transmitted to the subunit interfaces resulting in the rupture of two electrostatic bonds that stabilize the T state. The equilibrium between the two states then shifts towards the R state. As more oxygen binds, two new electrostatic bonds and one hydrophobic interaction are weakened and there is a further shift in the T-R equilibrium. Thus the oxygen affinity increases with increasing saturation of haemoglobin...ith increasing saturation of haemoglobin................................................... --This animation shows the effect pH on oxygen binding "HMr" "O21" "O22" "H1" -125, 2790 "H2" 8995, 2790 "H3" 8995, 1880 3595, 1895 3595, 1895, 4000, 2270 4570, 1895 "HMh1" "HMh2" "HMh3" "HMt" "HM1" "text1" "text2" "text3" "text4" "textGo" --A hydrogen comes along binds fR state haemoglobin 140, 2790 470, 2430 810, 2320 1265, 2430 1585, 2520 1825, 2790 2005, 2430 2245, 2320 2415, 2430 2630, 2520 2960, 2790 beta subunit which bound tries change its conformation but fails 3366, 2515, 4296, 3460 3321, 2515, 4296, 3460 8355, 2790 7725, 2430 7530, 2320 7170, 2430 6990, 2520 6825, 2790 6675, 2430 6495, 2320 6030, 2430 5680, 2520 5310, 2790 --On ion, alpha fattached hydrogens convert 4296, 2505, 5181, 3460 3366, 2515, 4296, 3460 3321, 2515, 4296, 3460 4296, 2505, 5271, 3460 --following conformational subunits whole molecule --now 8225, 1880 7775, 1515 7415, 1375 7005, 1515 6825, 1650 6500, 1880 6290, 1515 5955, 1375 5695, 1515 5380, 1650 5210, 1880 --Now that molecules are released ZhorizPos ZvertPos 4570 8970 forced 3640, 1895, 3965, 2270 3595, 1895, 4000, 2270 3640, 1895, 3965, 2270 3595, 1895, 4000, 2270 3640, 1895, 3965, 2270 3595, 1895, 4000, 2270 3640, 1895, 3965, 2270 2845, 1895 2760, 1895, 3165, 2270 2760 -260 H-100 , 1895 3595, 1895, 4000, 2270 default buttonUp buttonUp text1 text2 text3 text4 textGo text1 text2 text2 text3 text3 text4 text4 textGo default horizPos:by horizPos:to vertPos horizPos 5dLZX ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Interaction of BPG with the T state of Haemoglobin a NH His 2 His 143 His 2 His 143 TJo $ 8D/ DvD}D B DR Lys 82 Lys 82 --these situation between oxygen tension BPG=5 shows decreasing 40mmHg change made bpg=5 M=100 "1"=5580 "2"=4470 "barchart" 5760, 3450, 6735, 3750 "HM1" "HM2" "HM4" "HM5" "HM12" "HM22" "HM42" "HM52" "HM11" "HM21" "HM31" "HM41" "HM51" further "1"=5580 "2"=5760 6225, 3450, 6735, 3750 returns 6bar ( "1"=5580 "2"=6225 4470, 3450, 6735, 3750 occurs "1"=4470 "2"=4470 5760, 3450, 6735, 3750 "1"=4470 "2"=5760 6225, 3450, 6735, 3750 "1"=4470 "2"=6225 "Barchart" 4470, 3450, 6735, 3750 "1"=6720 "2"=4470 5760, 3450, 6735, 3750 "1"=6720 "2"=5760 6225, 3450, 6735, 3750 "1"=6720 "2"=6225 4470, 3450, 6735, 3750 buttonUp buttonUp barchart barchart barchart barchart barchart Barchart barchart barchart barchart ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The Bohr Effectrotons on the Oxygen Affinityyynnnnnnnnnnnnn Hydrogen ions also have an effect on the T-R equilibrium. The transition from T state to R state involves the release of approximately one hydrogen ion per subunit. Thus, because hydrogen ions are involved in the T-R state transition, their concentration and therefore the pH will influence the position of that equilibrium. Lower pH (higher hydrogen ion concentration) will favour formation of the T state. This in turn will reduce the oxygen affinity of haemoglobin..... The next few pages illustrate the Bohr effect. BPG & altitude "Ap45" "Ap75" "Ap90" "VO290" "VO21" "Everest" "Nanda Devi" "Matterhorn" "sea" "Altitude" enterPage enterPage VO290 Everest Nanda Devi Matterhorn Altitude text1 However, at these altitudes, the venous pO decreases, therefore allowing Hb to deliver approximately 20% oxygen to the stressed tissues.lood.ry.ry.........2 decreases to allow 20% oxygen to be unloaded. text1 At an altitude of 9000m, the difference between arterial and venous pO is so small that only approximately 5% oxygen is unloaded by Hb.ood.ry.ry.........2 decreases to allow 20% oxygen to be unloaded. As the altitude increases the effect of increased BPG concentration cannot help, therefore the amount of oxygen unloaded by Hb declines..blood.ry.ry.........2 decreases to allow 20% oxygen to be unloaded. text1 When the arterial pO drops to 55mmHg, as it does at an altitude of 4500m, the amount of oxygen unloaded is reduced to 30% in non-adapted blood.y.ry.........2 decreases to allow 20% oxygen to be unloaded. change alltitude Change Altitude Altitude Altitude 0000m Sea level Everest Everest R!*!O! (mm Hg) % Saturation n%F%k% Z&2&W& Nanda Devi Nanda Devi Normal BPG High BPGGG Amount of O unloaded eeeeee VO290 Venous pO at 9000m Arterial pO at 9000mmmllll Arterial pO at 7500mmmllll Venous pO D6:6A6 Venous pO Arterial pOt sea levellllll Arterial pO at 4500mmmllll Matterhorn Matterhornnn High altitude adaptation raises the (BPG), which decreases the affinity of Hb for O .The amount of O unloaded is thus restored to 38% of its maximum load................................ At sea level, where arterial and venous pO values are 100 and 30mmHg respectively, Hb normally unloads 38% of the oxygen it can carry maximally..;F You can distribute the unmodified material freely and modify it to your own requirements. However, we ask the following: 1. By all means give yourself credit for your work in your books but please leave this page unaltered in this book. 2. It is important that teaching material of this kind is disseminated as widely as possible, so please ensure that your material is also freely available. 3. Please send a copy of any modified or expanded versions of this program to Dr J.M Basford, Department of Biochemistry, University of Wales, Cardiff, CF1 1ST , Tel 44 222-874119 Fax 44 222-874116. Internet Basford @Cardiff.ac.uk default buttonUp buttonUp default Continue :PHYSSIZE Teaching and Learning Technology Programme Haemoglobin default buttonUp buttonUp default Start produced by the R. Emma Thomas & John M. Basford Biochemistry Department University of Wales, Cardiff............ "rp1" 3050, 2350 "rp2" -1210, 2425 "rp3" -5890, 2405 "O2" 5025, 2115 "plasma" 4785, 2340, 5510, 2795 "plasma2" 4875, 1815, 5855, 2475 cell" 2790, 2055, 3765, 2745 cell2" "box1" "box2" "key" "text1" "text2" "text3" "textGo" --illustration begins fthe flow blood cells through a vessel. H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 H200, 0 shows amount oxygen carried a volume equivelant -- a sysLockSceen 5145, 1395, 6380, 2310 "O2" 5355, 1680 5505, 885, 7505, 2205 "O2" 5895, 1305 5640, 585, 8225, 2145 "O2" 6210, 1065 syslockScreen 5685, 255, 8510, 2100 "O2" 6435, 750 5640, 585, 8225, 2145 "O2" 6210, 1065 5505, 885, 7505, 2205 "O2" 5895, 1305 5145, 1395, 6380, 2310 "O2" 5355, 1680 4875, 1815, 5855, 2475 "O2" 5025, 2115 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 illustrates 2250, 1455, 3570, 2475 1410, 1005, 3345, 2295 735, 540, 3135, 2130 285, 255, 3075, 2100 735, 540, 3135, 2130 1410, 1005, 3345, 2295 2250, 1455, 3570, 2475 2790, 2055, 3765, 2745 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 H250, 0 default buttonUp buttonUp plasma plasma2 red cell plasma plasma2 red cell red cell2 text1 text2 text3 textGo text1 text2 plasma plasma plasma2 plasma2 333333 plasma2 333333 plasma2 333333 plasma2 plasma2 333333 plasma2 333333 plasma2 333333 plasma2 plasma2 plasma plasma text2 text3 red cell red cell red cell2 red cell 333333 red cell2 333333 red cell2 333333 red cell2 red cell2 333333 red cell2 red cell red cell2 333333 red cell 333333 red cell red cell text3 textGo default sysLockSceen ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Haem Molecule The central iron atom is in the Fe(II) state and is coordinated to four nitrogen atoms from the porphyrin ring and one nitrogen from the proximal histidine residue in the globin subunit. The sixth coordination position is unoccupied until it binds oxygen.......................position is unoccupied until it binds oxygen. "text1" "Arrow" 7670, 4150 "RT1" "RT2" "RT3" "RT4" "TR1" "TR2" "TR3" "TR4" "text2" "text3" enterPage enterPage text1 Arrow text2 text3 .v022 text3 At pH 7.2 and higher proton conc. more Hb molecules shift to the T state and as a result release their oxygen. The T:R ratio rises to 5:111111111111111111111111111111111e T state. text2 At pH 7.4, the H ions promote the transition from R to T state and thus the release of oxygen from Hb molecules, thereby making the ratio approx. 2:1. favour of the T state. T state R statee Arrow Animation5 Change pH The Effect of pH on the T to R Equilibrium Press the "Change pH" button. R H q b#H n%H q "'H q ~(H :*H text1 text1 At pH 7.6 and a pO of 40mmHg the T-R state ratio for haemoglobin is 1:1. ween both conformational states (T and R). tional states (T and R). Introduction Introduction ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page In mammals the delivery of adequate amounts of oxygen to working tissues is of primary importance. The ability to deliver this oxygen is entirely dependent upon the capacity of red blood cells both to take up large quantities of oxygen in the lungs and to release most of this oxygen under the conditions in the working tissues. In working tissues the oxygen concentration is much lower, the pH is lower and the carbon dioxide concentration is much higher than in the lungs. The ability of red cells to deliver oxygen and to alter the magnitude of this delivery according to the conditions is dependent on the properties of haemoglobin, a protein exquisitely suited to this role. "quest15" "quest16" leavePage leavePage quest15 quest16 quest15 quest16 15. After acclimatisation at an altitude of 4500m what effects occur ? The BPG concentration in red cells increases The amount of oxygen taken up in the lungs decreases The amount of oxygen unloaded remains the same The amount of oxygen unloaded increases The pH value decreasessssssss 16. Which amino acid residue in the b subunit interacts with a hydrogen ion and is implicated in the Bohr effect? Lysine Arginine Histidine Valine Glycine NextPage 4questscore15 4questscore16 B"15a" B"15b" B"15c" B"15d" B"15e" B"16a" B"16b" B"16c" B"16d" B"16e" default buttonUp buttonUp default questscore16 questscore15 backPage Previous default buttonUp buttonUp Previous default NextPage default buttonUp buttonUp default "7.6" enterPage enterPage A lowering of pH shifts the oxygen dissociation curve to the right, so that the oxygen affinity is decreased, therefore more O is unloaded in the tissues. change pH animation illustrates the effect pH on percentage --oxygen released 6tissues. shows Vsituation cpH decreases change occurs only pH=7.6 "7.4" pH=7.4 "7.2" pH returns pH=7.2 "7.6" buttonUp buttonUp Change pH 7.60m Arterial pO in capillaries llll Amount of O unloaded eeeeee pH 7.6 pH 7.4 pH 7.2 text1 At pH 7.2, Haemoglobin releases about 10% more oxygen at the arterial pO of 20mmHg in active muscles than it does at pH 7.4........................................ text1 In the capillaries where pO is low, the H ions generated by bicarbonate formation are taken up by Hb, which is thus induced to unload its bound oxygen.... % Saturation V . S #X#}# l$D$i$ (mm Hg) (Torr) illustration3 ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Structure of BPG with Deoxyhaemoglobin 2,3 - Bisphosphoglycerate (BPG) The binding site for BPG is constituted by three positively charged residues on each b chain: the a-amino group, Lysine 82, and histidine 143. These groups interact with the strongly negatively charged BPG, which carries nearly four negative charges at physiological pH. The following page illustrates how BPG binds to the T state of haemoglobin........nnnnn.. enterPage enterPage [8Y8Y*\*\ The Interaction Between Protons and Haemoglobinnnnnnnnnnnnn ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page C-terminal { d!9 MOVE ON TO NEXT PAGE AT ANY TIMEEEEEEEEEE T state(deoxy)) R state (oxy) C-terminal JX"XGX Aspartate 94 raises the pK of Histidine 146 in deoxyhaemoglobin, but not in oxyhaemoglobin. The proximity of the ve charge on Asp 94 favours protonation of His 146 in deoxyHb.Thus, in the transition from oxy to deoxyHb, His 146 acquires a greater affinity for H because its local environment becomes more vely charged.........................dddddd "Arrow"= 7670 6920, 4150 "text1" "text2" "text3" "RT1" "RT2" "RT3" "RT4" "TR1" "TR2" "TR3" "TR4" ZhorizPos 5405 2150 H-105 -, 1170 syslockScreen 5405, 1170 nthe 4820, 2415 4100, 2640 3230, 2475 2420, 2175 1895, 2010 5120, 2010 6200, 4150 ZvertPos 7370 3035 7370, 1050 6050 2975 H-123 , 2475 6050, 2475 7670, 4150 2975 6050 , 2475 2975, 2475 3035 7370 3035, 1395 2420, 2175 3230, 2475 4100, 2640 4820, 2415 5120, 2010 1895, 2010 2150 5405 , 1170 2150, 1170 default buttonUp buttonUp Arrow Arrow text1 text2 text3 Arrow Arrow text3 text2 text1 Arrow Arrow text1 text3 text2 default vertPos horizPos:by1 horizPos:to1 horizPos PdoHQd HAEMOGLOBIN Times New Roman System Times New Roman Times New Roman Times New Roman System Times New Roman Symbol Times New Roman Times New Roman Wingdings Wingdings Times New Roman Times New Roman Wingdings Times New Roman Arial Symbol Arial Times New Roman Times New Roman System Arial System Arial Times New Roman System Times New Roman System System System Symbol Times New Roman Times New Roman Times New Roman Times New Roman Times New Roman Symbol Arial mes New Roman Symbol Times New Roman Times New Roman Times New Roman Times New Roman Times New Roman Wingdings backPage Previous default buttonUp buttonUp Previous default NextPage default buttonUp buttonUp default barchart Change BPG concentration Change (BPG))) v $ b T state R state mmHg (Torr) mM/ml text6 At a pO of 40mmHg when BPG is absent, Haemoglobin is found to be between 75% saturated and fully oxygenated. text3 Even if BPG were absent at a pO of 100mmHg, Haemoglobin would remain to be found all in the R state and fully oxygenated.... text2 A higher BPG concentration of 10mM has no effect on the T to R equilibrium when pO is 100mmHg. Thus Hb is all in the R state and fully oxygenated. text1 At a BPG concentration of 5mM (its normal concentration) and a pO of 100mmHg, Haemoglobin is all in the R state and fully oxygenated. text9 At a pO of 20mmHg where BPG is absent, Haemoglobin is found to be mainly 50% saturated and flickering between the R and T state. text7 At a pO of 20mmHg and a BPG concentration of 5mM Haemoglobin is found to be mainly 25% saturated and in the T state. text8 In highly active tissues, where pO =20mmHg, 10mM BPG shifts the equilibrium almost entirely to the T state, inducing Hb to unload all its bound oxygen. text4 At a pO of 40mmHg and a (BPG) of 5mM, the T to R equilibrium shifts towards the T state. Hb is approx 75% saturated with O and mostly in the R state...... text5 At a pO of 40mmHg and a (BPG) of 10mM, the shift to the T state is greater. Hb is found to be approx 50% saturated with O and with a T:R ratio of 1:1.. T state.ng between the R and the T state. Change Oxygen tension Change tensionnn # :4h Oxygenated Deoxygenated Concccc "text1" "textGo" "text2" "text3" "text4" "text5" "text6" "O21" nthe -470, 210 "O22" 7480, 200 "O23" 8450, 2725 "O24" -520, 2170 "HM1" "HM2" "HM3" "HM31" "HM4" "HM5" 370, 1330 820, 1435 1300, 1525 1855, 1600 2440, 1660 2920, 1720 3220, 1795 3295, 1795, 3605, 2200 3190, 1795, 3605, 2200 3295, 1795, 3605, 2200 3190, 1795, 3605, 2200 3295, 1795, 3605, 2200 3970, 1795 3865, 1795, 4295, 2200 7865, 1390 7460, 1540 6980, 1690 6515, 1750 6065, 1750 5495, 1795 5495, 1795, 5840, 2200 5495, 1795, 5915, 2200 5495, 1795, 5840, 2200 5495, 1795, 5915, 2200 5495, 1795, 5840, 2200 4865, 1810 4865, 1810, 5270, 2215 ZhorizPos 8865 4865 H-100 2, 2710 -565 3865 , 2710 default buttonUp buttonUp text1 textGo text2 text3 text4 text5 text6 text1 text2 text2 text3 text3 text4 text4 text5 text6 text5 text6 textGo default horizPos:by horizPos:to horizPos Buttons Used In The Following Pagess ExitProgram backPage NextPage FirstPage 1st Page Move to the next page Return to previous page Return to the first page of Exit to Windows Animate Animate Animates the sequence of events on that page Go on to the next page by clicking the button below: backPage Previous default buttonUp buttonUp Previous default NextPage default buttonUp buttonUp default ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page Hotwords - These are words that are scattered round the text and are shown in italic, bold, underlined type and are larger than the surrounding text. They become active when the mouse operated cursor is placed over them. Try pressing this Hotword now! -- Puts the sentence quotation marks a dialog box which can be removed Hclicking "Activating a HOTWORD will present you dthat may contain definitions, references, hints tips, prompts other forms encouragement. Press OK buttonDown buttonDown Activating a HOTWORD will present you with a dialog box that may contain definitions, references, hints and tips, prompts or other forms of encouragement. Press OK to continue pf&h&h& "text1" SHOW GROUP "O21" nthe -470, 210 "O22" 7480, 200 "O23" 8450, 2725 "O24" -520, 2170 "Text "HM1" "HM2" "HM3" "HM4" "HM31" "HM5" "text2" "text3" "text4" "text5" "text6" "textGo" enterPage enterPage text1 Text end text2 text3 text4 text5 text6 textGo r t $ Animation3 Animate Press the "Animate" button. Cooperative Oxygen Bindingggggggggggggggggggggggggggggggg T state R state Text end REPEAT ANIMATION OR MOVE ON TO NEXT PAGEE textGo REPEAT ANIMATION OR MOVE TO THE NEXT PAGEEE text2 DeoxyHb is a taut molecule, constrained by eight salt links. Oxygenation does not readily occur unless some salt links are broken.e broken text6 text4 Unliganded subunits in the R state have an increased oxygen affinity because they are already in the O --binding conformation. text5 All the subunits are converted to the R state whether they are liganded or not.nliganded subunits in the R state have an increased O a text4 text4 As more O binds, the strain, derived from the Fe--O bond energy,increases until it is of sufficient strength to snap haemoglobin into the R state................. text3 This is because salt links must be broken to permit the binding of the first O . Fewer salt links have to be broken for the binding of subsequent oxygens. y text2 The R state of haemoglobin has a much higher affinity for O than the T state. Therefore the binding of the first O molecule to the T state is difficult.es.getically less favoured than that of subsequent oxygen molecules.lly less favoured than that of subsequent oxygen molecules. text1 The binding of O to haemoglobin enhances the binding of additional O to the same Hb molecule. i.e oxygen binds cooperatively to haemoglobin....... Oxygenated Deoxygenated "text1" "textGo" "HM1" "HM11" "HM12" "HM13" "HM2" "HM21" "HM22" "HM23" "HM3" "HM31" "HM32" "HM33" "HM4" "HM41" "HM42" "HM43" "HM4a" "HM41a" "HM42a" "HM43a" "HM5" "HM51" "HM52" "Arrow" 4520, 4120 m"L2" m"L3" m"L4" "p50" enterPage enterPage text1 textGo HM41a HM42a HM43a Arrow &L'x' '((T( (|)z*x+v, HM43a # R!W Animation4 Animate Press the "Animate" button. Q **n HM41a HM42a Q &,V T state R state p/H/m/ (mm Hg) (Torr) r0J0o0 ^161[1 Arrow textGo REPEAT ANIMATION OR MOVE TO THE NEXT PAGEEE text3 Haemoglobin is 50% saturated at an oxygen partial pressure of 26mmHg (Torr). At 100mmHg p O , haemoglobin is 95% saturated. text2 The O dissociation curve of Hb is sigmoidal in shape.Thus the amount of O bound by Hb changes significantly over a relatively small range of p O . text1 The oxygen saturation of haemoglobin depends on the partial pressure of oxygen(p O ) than it would if O binding sites were independant of each other.................... "Arrow" nthe 4520, 4120 "HM1" "HM11" "HM12" "HM13" "HM2" "HM21" "HM22" "HM23" "HM3" "HM31" "HM32" "HM33" "HM4" "HM41" "HM42" "HM43" "HM4a" "HM41a" "HM42a" "HM43a" "HM5" "HM51" "HM52" m"L2" m"L3" m"L4" "p50" "text1" "text2" "text3" "textGo" moves along "Oxygen tension" axis ZhorizPos 4520 5420 -, 4120 --conformational change one alpha chain %oxygen binds syslockScreen continues 5420 5735 , 4120 m"L2" 5735 6080 , 4120 m"L3" 6080 6935 , 4120 m"L4" --final oxyhaemoglobin 6935 7850 , 4120 deoxyhaemoglobin undergoes default buttonUp buttonUp Arrow HM41a HM42a HM43a text1 text2 text3 textGo text2 text1 Arrow text3 text2 Arrow HM41a HM42a HM43a Arrow HM41a HM42a HM43a Arrow Arrow text3 textGo default horizPos:by horizPos:to horizPos illustration1 "Deoxy" "Oxy" terPage enterPage leavePage enterPage Deoxy Deoxy Deoxy leavePage Deoxy When the sixth coordination position is occupied by oxygen the iron atom moves into the plane of the haem molecule. The proximal histidine (F8) is pulled along with the iron atom and becomes less tilted. This movement initiates the conformational change from the T state to the R state. Histidine F8 Porphyrin planee ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page MOVE ON TO NEXT PAGE AT ANY TIMEEEEEEEEEE Deoxy barchart --the equilibrium between deoxyhaemoglobin varies depending --on Aconcentration Xblood. --changing llength vorange bar ( /) causes a alteration --these situation oxygen tension=100 shows increasing change made bpg=5 G=100 "1"=5580 "2"=4470 "barchart" 4470, 2445, 6735, 2745 "HM1" "HM2" "HM4" "HM5" "HM12" "HM22" "HM42" "HM52" "HM11" "HM21" "HM31" "HM41" "HM51" "text2" "text1" "text3" "text4" "text5" "text6" "text7" "text8" "text9" decreasing occurs BPG=10 "1"=4470 "2"=4470 6720, 2445, 6735, 2745 returning "1"=6720 "2"=4470 5580, 2445, 6735, 2745 40mmHg "1"=5580 "2"=5760 4470, 2445, 6735, 2745 "1"=4470 "2"=5760 6720, 2445, 6735, 2745 "1"=6720 "2"=5760 5580, 2445, 6735, 2745 increase "1"=5580 "2"=6225 4470, 2445, 6735, 2745 "1"=4470 "2"=6225 6720, 2445, 6735, 2745 "1"=6720 "2"=6225 5580, 2445, 6735, 2745 buttonUp buttonUp barchart text2 text1 text3 text4 text5 text6 text7 text8 text9 barchart text3 text1 text2 text4 text5 text6 text7 text8 text9 barchart text1 text2 text3 text4 text5 text6 text7 text8 text9 barchart text5 text1 text3 text4 text2 text6 text7 text8 text9 barchart text6 text1 text3 text4 text5 text2 text7 text8 text9 barchart text4 text1 text3 text2 text5 text6 text7 text8 text9 barchart text8 text1 text3 text4 text5 text6 text7 text2 text9 barchart text9 text1 text3 text4 text5 text6 text7 text8 text2 barchart text7 text1 text3 text4 text5 text6 text2 text8 text9 illustration2 terPage enterPage leavePage enterPage leavePage MOVE ON TO NEXT PAGE AT ANY TIMEEEEEEEEEE T state R state ExitProgram "Really quit?"\ f"Yes" SysSuspendMessages buttonUp buttonUp Really quit? FirstPage buttonUp buttonUp 1st Page The a b contact acts as a binary switch that permits only two stable positions of the subunits relative to each other. Oxygenation causes a switch from the T to the R state.The structural changes accompanying the T to R transition break the salt links in a process driven by the Fe O bond's energy of formation. tiny "System $%%%%% ''$'$'$'$$ '$'$$$$ $'''' $$$'$ $$$''' $$''% ? ? ??? ? '$$$' ? ? ??? ? ? ? ? $$$$''% ? ? ? ? ? ? ? ? ? %%% ? ? ? ? ?% ? ? ? ? ? ? ?% ? ? ? ? % ? ? $'%%' ? ? ? MMJJKKwJ PSRS[ ]MKPPRSZVV YPRRZ `KJSSZjc__ YRSVeqj_L{ eJPRV_QQl_ \PPSVKQQc_ YiRSV_QQqcZ YYRSdsQQj_ Y]fRV_QQQc_ \PPSNlQQj_ ? ?? 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