2acy
From Proteopedia
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ACYL-PHOSPHATASE (COMMON TYPE) FROM BOVINE TESTIS
Overview
BACKGROUND: Acylphosphatase (ACP) is a low molecular weight, phosphomonohydrolase catalyzing with high specificity the hydrolysis of, the carboxyl-phosphate bond present in acylphosphates. The enzyme is, thought to regulate metabolic processes in which acylphosphates are, involved, such as glycolysis and the production of ribonucleotides., Furthermore the enzyme is capable of hydrolyzing the phospho-aspartyl, intermediate formed during the action of membrane pumps such as, (Ca2++Mg2+) ATPase. Although the tertiary structure of a muscle ACP has, been determined by NMR spectroscopy, little is known about the catalytic, mechanism of ACP and further structures might provide an increased, understanding. RESULTS: The structure of 'common type' ACP from bovine, testis has been determined by X-ray crystallography to a resolution of 1.8, A. The structure has been refined to an R factor of 17.0 % using all data, between 15 and 1.8 A. The binding of a sulphate and a chloride ion in the, active centre allows a detailed description of this site. The overall, protein folds of common type and muscle ACP are similar but their loops, have very different conformations. These differences, in part, are, probably caused by the binding of the ions in the active site of the, common type form. The phosphate-binding loop of ACP shows some remarkable, similarities to that of low molecular weight protein tyrosine phosphatase., CONCLUSIONS: The active site of ACP has been located, enabling a reaction, mechanism to be suggested in which the phosphate moiety bound to Arg23, acts as a base, abstracting a proton from a nucleophilic water molecule, liganded to Asn41. The transition-state intermediate is stabilized by the, phosphate-binding loop. We suggest the catalysis to be substrate assisted, which probably explains why this enzyme can only hydrolyze acylphosphates.
About this Structure
2ACY is a Single protein structure of sequence from Bos taurus with SO4 and CL as ligands. Active as Acylphosphatase, with EC number 3.6.1.7 Full crystallographic information is available from OCA.
Reference
Crystal structure of common type acylphosphatase from bovine testis., Thunnissen MM, Taddei N, Liguri G, Ramponi G, Nordlund P, Structure. 1997 Jan 15;5(1):69-79. PMID:9016712
Page seeded by OCA on Wed Nov 21 08:03:18 2007
