Conformational Flexibility in the Active Sites of Aspartyl Proteinases Revealed by a Pepstatin Fragment Binding to Penicillopepsin

Crystals of the molecular complex between the esterified tripeptide fragment of pepstatin and the aspartyl proteinase penicillopepsin are isomorphous with crystals of native penicillopepsin. The difference electron-density map at 1.8- angstrom resolution, computed by using the amplitude differences...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1982-10, Vol.79 (20), p.6137-6141
Main Authors: Michael N. G. James, Sielecki, Anita, Salituro, Frank, Rich, Daniel H., Hofmann, Theo
Format: Article
Language:English
Subjects:
Active sites
Amino acids
Aspartic Acid Endopeptidases
Atoms
Binding Sites
Biochemistry
Crystal structure
Crystals
Electrical phases
Endopeptidases
Enzymes
Hydrogen bonds
Models, Molecular
Molecules
Motion
Oligopeptides
Pepstatins
Protease Inhibitors
Protein Binding
Protein Conformation
X-Ray Diffraction
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Crystals of the molecular complex between the esterified tripeptide fragment of pepstatin and the aspartyl proteinase penicillopepsin are isomorphous with crystals of native penicillopepsin. The difference electron-density map at 1.8- angstrom resolution, computed by using the amplitude differences and refined phases of reflections from the crystal of native penicillopepsin, unambiguously showed the binding mode of isovaleryl-Val-Val-StaOEt, where StaOEt is the ethyl ester of statine [(4S,3S)-4-amino-3-hydroxyl-6-methylheptanoic acid]. In addition, a major conformational change in penicillopepsin involving the large β loop of residues from Trp-71 to Gly-83 (the so-called ``flap'' region) occurs as a result of this inhibitor binding. This structural movement provides the first confirmation of the importance of enzyme flexibility in the aspartyl proteinase mechanism. The 3-hydroxyl group of the Statine residue and the carbonyl oxygen atom of the ethyl ester are situated on either side of the approximate plane containing the hydrogen-bonded carboxyl groups of Asp-33 and Asp-213. The observed binding mode of the pepstatin tripeptide fragment is similar to that predicted for the binding of good substrates with penicillopepsin [James, M. N. G. (1980) Can. J. Biochem. 58, 251-271].
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.79.20.6137