1fq7
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X-RAY STRUCTURE OF INHIBITOR CP-72,647 BOUND TO SACCHAROPEPSIN
OverviewOverview
Saccharopepsin is a vacuolar aspartic proteinase involved in activation of, a number of hydrolases. The enzyme has great structural homology to, mammalian aspartic proteinases including human renin and we have used it, as a model system to study the binding of renin inhibitors by X-ray, crystallography. Five medium-to-high resolution structures of, saccharopepsin complexed with transition-state analogue renin inhibitors, were determined. The structure of a cyclic peptide inhibitor (PD-129,541), complexed with the proteinase was solved to 2.5 A resolution. This, inhibitor has low affinity for human renin yet binds very tightly to the, yeast proteinase (K(i)=4 nM). The high affinity of this inhibitor can be, attributed to its bulky cyclic moiety spanning P(2)-P(3)' and other, residues that appear to optimally fit the binding sub-sites of the enzyme., Superposition of the saccharopepsin structure on that of renin showed that, a movement of the loop 286-301 relative to renin facilitates tighter, binding of this inhibitor to saccharopepsin. Our 2.8 A resolution, structure of the complex with CP-108,420 shows that its benzimidazole P(3, )replacement retains one of the standard hydrogen bonds that normally, involve the inhibitor's main-chain. This suggests a non-peptide lead in, overcoming the problem of susceptible peptide bonds in the design of, aspartic proteinase inhibitors. CP-72,647 which possesses a basic, histidine residue at P(2), has a high affinity for renin (K(i)=5 nM) but, proves to be a poor inhibitor for saccharopepsin (K(i)=3.7 microM). This, may stem from the fact that the histidine residue would not bind, favourably with the predominantly hydrophobic S(2) sub-site of, saccharopepsin.
About this StructureAbout this Structure
1FQ7 is a Single protein structure of sequence from Saccharomyces cerevisiae with NAG, BOC, PHE, HIS, CAL and NME as ligands. Active as Saccharopepsin, with EC number 3.4.23.25 Full crystallographic information is available from OCA.
ReferenceReference
X-ray structures of five renin inhibitors bound to saccharopepsin: exploration of active-site specificity., Cronin NB, Badasso MO, J Tickle I, Dreyer T, Hoover DJ, Rosati RL, Humblet CC, Lunney EA, Cooper JB, J Mol Biol. 2000 Nov 10;303(5):745-60. PMID:11061973
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