5est
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(New page: 200px<br /><applet load="5est" size="450" color="white" frame="true" align="right" spinBox="true" caption="5est, resolution 2.09Å" /> '''CRYSTALLOGRAPHIC ANA...)
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Revision as of 17:23, 20 November 2007
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CRYSTALLOGRAPHIC ANALYSIS OF THE INHIBITION OF PORCINE PANCREATIC ELASTASE BY A PEPTIDYL BORONIC ACID: STRUCTURE OF A REACTION INTERMEDIATE
Overview
The crystal structure of porcine pancreatic elastase (PPE) complexed to, carbobenzoxy-alanylisoleucine-boronic acid (ZAIB) is reported to 2.09-A, resolution and refined to an R factor of 0.15. This is the first reported, structural analysis of PPE with an isoleucine residu in the primary, specificity pocket. The results include (1) marked displacement of the, inhibitor out of the active site leading to (2) a close (2.2 A) direct, contact between B (boron atom of the inhibitor) and N epsilon of His-57, and also (3) covalent bonding (1.5 A) to O gamma of Ser-195. A scheme for, the mechanism of inhibition of PPE by ZAIB is proposed. A comparison with, a peptidyl difluoromethyl ketone-PPE complex (Ki = 9.5 microns) is made to, explain the strong inhibition of PPE by ZAIB (Ki = 0.3 micron). These, results lead us to characterize this structure as a time- and, space-averaged reaction intermediate, providing fresh insight into the, cramped dimensions available in enzymatic catalyses.
About this Structure
5EST is a Single protein structure of sequence from [1] with SO4 and CA as ligands. Active as Pancreatic elastase, with EC number 3.4.21.36 Full crystallographic information is available from OCA.
Reference
Crystallographic analysis of the inhibition of porcine pancreatic elastase by a peptidyl boronic acid: structure of a reaction intermediate., Takahashi LH, Radhakrishnan R, Rosenfield RE Jr, Meyer EF Jr, Biochemistry. 1989 Sep 19;28(19):7610-7. PMID:2611205
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