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M9470070.TXT
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1994-07-02
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Document 0070
DOCN M9470070
TI Alternative native flap conformation revealed by 2.3 A resolution
structure of SIV proteinase.
DT 9409
AU Wilderspin AF; Sugrue RJ; Department of Crystallography, Birkbeck
College, London, England.
SO J Mol Biol. 1994 May 27;239(1):97-103. Unique Identifier : AIDSLINE
MED/94254094
AB A large conformational change is observed between HIV-1 proteinase in
the ligand-free state and in complexes with transition-state inhibitors.
Crystal structures of this enzyme have either the flaps open for the
native or ligand-free enzyme or the flaps closed for peptidomimetic
ligand-bound enzyme. We describe the structure of native recombinant SIV
proteinase which like other retroviral proteinases crystallizes as a
perfect 2-fold symmetric dimer but in a different crystal packing
arrangement. In contrast to HIV-1 PR we show that SIV proteinase in the
ligand-free state adopts the closed flaps conformation, demonstrating
that ligand binding is not a prerequisite for the closed flaps
conformation. The catalytic water was clearly observed between the two
aspartates which were not perfectly co-planar, and in this structure the
active site cleft is more restricted than for either inhibitor bound or
ligand-free HIV-1 proteinase. Accommodation of two bulkier side-chains
in the simian enzyme core has resulted in a more exposed N terminus than
for HIV-1 PR which we predict could enhance autocatalytic cleavage at
the N terminus.
DE Amino Acid Sequence Aspartic Proteinases/*CHEMISTRY/GENETICS Binding
Sites HIV Protease/GENETICS Models, Molecular Molecular Sequence Data
Molecular Structure *Protein Conformation Sequence Alignment Support,
Non-U.S. Gov't SIV/*ENZYMOLOGY JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).