9est
STRUCTURAL STUDY OF PORCINE PANCREATIC ELASTASE COMPLEXED WITH 7-AMINO-3-(2-BROMOETHOXY)-4-CHLOROISOCOUMARIN AS A NONREACTIVATABLE DOUBLY COVALENT ENZYME-INHIBITOR COMPLEX
|
OverviewOverview
The complex of porcine pancreatic elastase (PPE) with, 7-amino-3-(2-bromoethoxy)-4-chloroisocoumarin, a potent mechanism-based, inhibitor, was crystallized and the crystal structure determined at 1.9-A, resolution with a final R factor of 17.1%. The unbiased difference Fourier, electron density map showed continuous density from O gamma of Ser 195 to, the benzoyl carbonyl carbon atom and from N epsilon 2 of His 57 to the, carbon atom at the 4-position of the isocoumarin ring in the inhibitor., This suggested unambiguously that the inhibitor was doubly covalently, bound to the enzyme. It represents the first structural evidence for, irreversible binding of an isocoumarin inhibitor to PPE through both Ser, 195 and His 57 in the active site. The PPE-inhibitor complex is only, partially activated in solution by hydroxylamine and confirms the, existence of the doubly covalently bound complex along with the acyl, enzyme. The benzoyl carbonyl oxygen atom of the inhibitor is not situated, in the oxyanion hole formed by the amide (greater than NH) groups of Gly, 193 and Ser 195. The complex is stabilized by the hydrogen-bonding, interactions in the active site (from the N epsilon 2 of Gln 192 to the, bromine atom in the inhibitor and the amino group at the 7-position of the, isocoumarin ring to the carbonyl oxygen of Thr 41) and by van der Waals, interactions. The inhibition rates of several 7-substituted, 4-chloro-3-(bromoalkoxy)isocoumarins toward PPE were measured.(ABSTRACT, TRUNCATED AT 250 WORDS)
About this StructureAbout this Structure
9EST is a Single protein structure of sequence from Sus scrofa with SO4, CA and IBR as ligands. Active as Pancreatic elastase, with EC number 3.4.21.36 Full crystallographic information is available from OCA.
ReferenceReference
Structural study of porcine pancreatic elastase complexed with 7-amino-3-(2-bromoethoxy)-4-chloroisocoumarin as a nonreactivatable doubly covalent enzyme-inhibitor complex., Vijayalakshmi J, Meyer EF Jr, Kam CM, Powers JC, Biochemistry. 1991 Feb 26;30(8):2175-83. PMID:1998677
Page seeded by OCA on Tue Nov 20 13:02:33 2007