3er3
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(New page: 200px<br /><applet load="3er3" size="450" color="white" frame="true" align="right" spinBox="true" caption="3er3, resolution 2.0Å" /> '''THE ACTIVE SITE OF AS...)
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Revision as of 17:34, 20 November 2007
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THE ACTIVE SITE OF ASPARTIC PROTEINASES
Overview
The active site of the aspartic proteinase, endothiapepsin, has been, defined by X-ray analysis and restrained least-squares refinement at 2.1 A, resolution with a crystallographic agreement value of 0.16. The, environments of the two catalytically important aspartyl groups are, remarkably similar and the contributions of the NH2- and COOH-terminal, domains to the catalytic centre are related by a local 2-fold axis. The, carboxylates of the aspartyls share a hydrogen bond and have equivalent, contacts to a bound water molecule or hydroxonium ion lying on the local, diad. The main chains around 32 and 215 are connected by a novel, interaction involving diad-related threonines. It is suggested that the, two pKa values of the active site aspartyls arise from a structure not, unlike that in maleic acid with a hydrogen-bonded intermediate species and, a dicarboxylate characterised by electrostatic repulsions between the two, negatively charged groups.
About this Structure
3ER3 is a Single protein structure of sequence from [1]. Active as Hydrolase, with EC number 3.4.23.18, 3.4.23.28 and 3.4.23.30 3.4.21.103, 3.4.23.18, 3.4.23.28 and 3.4.23.30 Full crystallographic information is available from OCA.
Reference
The active site of aspartic proteinases., Pearl L, Blundell T, FEBS Lett. 1984 Aug 20;174(1):96-101. PMID:6381096
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