1fq7
X-RAY STRUCTURE OF INHIBITOR CP-72,647 BOUND TO SACCHAROPEPSIN
Structural highlights
FunctionCARP_YEAST Aspartyl protease implicated in the post-translational regulation of S.cerevisiae vacuolar proteinases. Acts on YSCB, on YSCY and on itself. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSaccharopepsin 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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