1a3g
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(New page: 200px<br /><applet load="1a3g" size="450" color="white" frame="true" align="right" spinBox="true" caption="1a3g, resolution 2.5Å" /> '''BRANCHED-CHAIN AMINO ...)
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Revision as of 08:28, 20 November 2007
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BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE FROM ESCHERICHIA COLI
Overview
The X-ray crystallographic structure of the branched-chain amino acid, aminotransferase from Escherichia coli was determined by means of, isomorphous replacement using the selenomethionyl enzyme as one of the, heavy atom derivatives. The enzyme is a homo hexamer with D3 symmetry, and, the polypeptide chain of the subunit is folded into two domains (small and, large domains). The coenzyme, pyridoxal 5'-phosphate, resides at the, domain interface, its re-face facing toward the protein. The active site, structure shows that the following sites can recognize branched-chain, amino acids and glutamate as substrates: (1) a hydrophobic core formed by, Phe36, Tyr164, Tyr31*, and Val109* for a branched-chain; (2) Arg97 for an, acidic side chain of glutamate; and (3) Tyr95 and two main chain NH groups, of Thr257 and Ala258 for the alpha-carboxylate of substrates. Although the, main chain conformation of the active site is homologous to that of, D-amino acid aminotransferase, many of the active site residues are, different between them.
About this Structure
1A3G is a Single protein structure of sequence from Escherichia coli with PLP as ligand. Active as Branched-chain-amino-acid transaminase, with EC number 2.6.1.42 Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of Escherichia coli branched-chain amino acid aminotransferase at 2.5 A resolution., Okada K, Hirotsu K, Sato M, Hayashi H, Kagamiyama H, J Biochem (Tokyo). 1997 Apr;121(4):637-41. PMID:9163511
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