1apv
|
CRYSTALLOGRAPHIC ANALYSIS OF TRANSITION STATE MIMICS BOUND TO PENICILLOPEPSIN: DIFLUOROSTATINE-AND DIFLUOROSTATONE-CONTAINING PEPTIDES
OverviewOverview
Difluorostatine- and difluorostatone-containing peptides have been, evaluated as potent inhibitors of penicillopepsin, a member of the, aspartic proteinase family of enzymes. Isovaleryl-Val-Val-StaF2NHCH3, [StaF2 = (S)-4-amino-2,2-difluoro-(R)-3-hydroxy-6-methylheptanoic acid], and isovaleryl-Val-Val-StoF2NHCH3 [StoF2 =, (S)-4-amino-2,2-difluoro-3-oxo-6-methylheptanoic acid] have measured Ki's, of 10 x 10(-9) and 1 x 10(-9) M, respectively, with this fungal, proteinase. The StoF2-containing peptide binds 32-fold more tightly to the, enzyme than the analogous peptide containing the non-fluorinated statine, ethyl ester. Each compound was cocrystallized with penicillopepsin, intensity data were collected to 1.8-A resolution, and the atomic, coordinates were refined to an R factor [formula: see text] of 0.131 for, both complexes. The inhibitors bind in the active site of penicillopepsin, in much the same fashion as do other statine-containing inhibitors of, penicillopepsin analyzed earlier [James, M. N. G., Sielecki, A. Salituro, F., Rich, D. H., & Hofmann, T. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 6137-6141; James, M.N.G., Sielecki, A., & Hofmann, T. (1985) in Aspartic, Proteinases and their Inhibitors (Kosta, V., Ed.) pp 163-177, Walter, deGruyter, Berlin]. The (R)-3-hydroxyl group in StaF2 binds between the, active site carboxyl groups of Asp33 and Asp213, making hydrogen-bonding, contacts to each one. The ketone functional group of the StoF2 inhibitor, is bound as a hydrated species, with the gem-diol situated between the two, aspartic acid carboxyl groups in a manner similar to that predicted for, the tetrahedral intermediate expected during the catalytic hydrolysis of a, peptide bond [James, M. N. G., & Sielecki, A. (1985) Biochemistry 24, 3701-3713]. One hydrogen-bonding interaction from the "outer" hydroxyl, group is made to O delta 1 of Asp33, and the "inner" hydroxyl group forms, two hydrogen-bonding contacts, one to each of the carboxyl groups of Asp33, (O delta 2) and Asp213 (O delta 2). The only structural difference between, the StaF2 and StoF2 inhibitors that accounts for the factor of 10 in their, Ki's is the additional (R)-3-OH group on the tetrahedral sp3 carbon atom, of the hydrated StoF2 inhibitor. The intermolecular interactions involving, the fluorine atoms of each inhibitor are normal van der Waals contacts to, one of the carboxyl oxygen atoms of Asp213 (F2-O delta 2 Asp213, 2.9 A)., The observed stereochemistry of the bound StoF2 group in the active site, of penicillopepsin has stimulated our reappraisal of the catalytic pathway, for the aspartic proteinases.(ABSTRACT TRUNCATED AT 400 WORDS)
About this StructureAbout this Structure
1APV is a Single protein structure of sequence from [1] with MAN, XYS, SO4 and DMF as ligands. Active as Penicillopepsin, with EC number 3.4.23.20 Full crystallographic information is available from OCA.
ReferenceReference
Crystallographic analysis of transition state mimics bound to penicillopepsin: difluorostatine- and difluorostatone-containing peptides., James MN, Sielecki AR, Hayakawa K, Gelb MH, Biochemistry. 1992 Apr 21;31(15):3872-86. PMID:1567842
Page seeded by OCA on Tue Nov 20 11:01:58 2007