4ape
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THE ACTIVE SITE OF ASPARTIC PROTEINASES
OverviewOverview
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 StructureAbout this Structure
4APE is a Single protein structure of sequence from Cryphonectria parasitica. This structure superseeds the now removed PDB entries 2APE and 1APE. The following page contains interesting information on the relation of 4APE with [Pepsin]. Active as Endothiapepsin, with EC number 3.4.23.22 Full crystallographic information is available from OCA.
ReferenceReference
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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