1s2b
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(New page: 200px<br /><applet load="1s2b" size="450" color="white" frame="true" align="right" spinBox="true" caption="1s2b, resolution 2.1Å" /> '''Structure of SCP-B th...)
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Revision as of 23:55, 20 November 2007
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Structure of SCP-B the first member of the Eqolisin family of Peptidases to have its structure determined
Overview
The molecular structure of the pepstatin-insensitive carboxyl peptidase, from Scytalidium lignicolum, formerly known as scytalidopepsin B, was, solved by multiple isomorphous replacement phasing methods and refined to, an R factor of 0.230 (R(free) = 0.246) at 2.1-A resolution. In addition to, the structure of the unbound peptidase, the structure of a product complex, of cleaved angiotensin II bound in the active site of the enzyme was also, determined. We propose the name scytalidocarboxyl peptidase B (SCP-B) for, this enzyme. On the basis of conserved, catalytic residues identified at, the active site, we suggest the name Eqolisin for the enzyme family. The, previously uninvestigated SCP-B fold is that of a beta-sandwich; each, sheet has seven antiparallel strands. A tripeptide product, Ala-Ile-His, bound in the active site of SCP-B has allowed for identification of the, catalytic residues and the residues in subsites S1, S2, and S3, which are, important for substrate binding. The most likely hydrolytic mechanism, involves nucleophilic attack of a general base (Glu-136)-activated water, (OH(-)) on the si-face of the scissile peptide carbonylcarbon atom to form, a tetrahedral intermediate. Electrophilic assistance and oxyanion, stabilization is provided by the side-chain amide of Gln-53. Protonation, of the leaving-group nitrogen is accomplished by the general acid function, of the protonated carboxyl group of Glu-136.
About this Structure
1S2B is a Single protein structure of sequence from Scytalidium lignicola. Active as Scytalidopepsin B, with EC number 3.4.23.32 Full crystallographic information is available from OCA.
Reference
The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum., Fujinaga M, Cherney MM, Oyama H, Oda K, James MN, Proc Natl Acad Sci U S A. 2004 Mar 9;101(10):3364-9. Epub 2004 Mar 1. PMID:14993599
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