1zg7
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Crystal Structure of 2-(5-{[amino(imino)methyl]amino}-2-chlorophenyl)-3-sulfanylpropanoic acid Bound to Activated Porcine Pancreatic Carboxypeptidase B
OverviewOverview
This paper presents the crystal structure of porcine pancreatic, carboxypeptidase B (pp-CpB) in complex with a variety of thiol-based, inhibitors that were developed as antagonists of activated, thrombin-activatable fibrinolysis inhibitor (TAFIa). Recent studies have, indicated that a selective inhibitor of TAFIa could enhance the efficacy, of existing thrombolytic agents for the treatment of acute myocardial, infarction, one of the most prevalent forms of heart attacks., Unfortunately, activated TAFIa rapidly degrades in solution and cannot be, used for crystallographic studies. In contrast, porcine pancreatic CpB is, stable at room temperature and is available from commercial sources. Both, pancreatic CpB and TAFIa are zinc-based exopeptidases, and the proteins, share a 47% sequence identity. The homology improves considerably in the, active site where nearly all of the residues are conserved. The inhibitors, used in this study were designed to mimic a C-terminal arginine residue, one of the natural substrates of TAFIa. The X-ray structures show that the, thiol group chelates the active site zinc, the carboxylic acid forms a, salt bridge to Arg145, and the guanidine group forms two hydrogen bonds to, Asp255. A meta-substituted phenyl was introduced into our inhibitors to, reduce conformational freedom. This modification vastly improved the, selectivity of compounds against other exopeptidases that cleave basic, residues. Comparisons between structures indicate that selectivity derives, from the interaction between the guanidine group in the inhibitors and an, acidic active site residue. The location of this acidic residue is not, conserved in the various carboxypeptidases.
About this StructureAbout this Structure
1ZG7 is a Single protein structure of sequence from Sus scrofa with ZN and P20 as ligands. Active as Carboxypeptidase B, with EC number 3.4.17.2 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of potent thiol-based inhibitors bound to carboxypeptidase B., Adler M, Bryant J, Buckman B, Islam I, Larsen B, Finster S, Kent L, May K, Mohan R, Yuan S, Whitlow M, Biochemistry. 2005 Jul 5;44(26):9339-47. PMID:15982000
Page seeded by OCA on Wed Nov 21 07:25:59 2007