Binding of a reduced peptide inhibitor to the aspartic proteinase from Rhizopus chinensis: implications for a mechanism of action.

• DOI: 10.1073/pnas.84.20.7009
• Publication Date: 2006-05-31T10:26:54Z
• Authors: K Suguna; E A Padlan; C W Smith; W D Carlson; D R Davies
• Keywords: Peptide bond

A peptide inhibitor, having the sequence D-His-Pro-Phe-His-Phe psi [CH2-NH]Phe-Val-Tyr, with a reduced bond between two adjacent phenylalanines, has been diffused into crystals of aspartic proteinase from Rhizopus chinensis (rhizopuspepsin, EC 3.4.23.6). X-ray diffraction data to 1.8-A resolution have collected on complex, which subjected restrained least-squares refinement an R-factor (R equals sum absolute value difference observed and calculated structure factor amplitudes divided by amplitudes) 14.7%. The inhibitor lies within major groove enzyme is clearly defined exception amino-terminal D-histidine carboxyl-terminal tyrosine. located in active site close contacts catalytic aspartyl groups. active-site water molecule that held carboxyl groups displaced as are number other molecules seen binding native enzyme. mechanism action for this class enzymes proposed these results.