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'''BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE FROM ESCHERICHIA COLI''' | '''BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE FROM ESCHERICHIA COLI''' | ||
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[[Category: Okada, K.]] | [[Category: Okada, K.]] | ||
[[Category: Sato, M.]] | [[Category: Sato, M.]] | ||
[[Category: | [[Category: Aminotransferase]] | ||
[[Category: | [[Category: Pyridoxal enzyme]] | ||
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Revision as of 06:45, 2 May 2008
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. 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. 1997 Apr;121(4):637-41. PMID:9163511 Page seeded by OCA on Fri May 2 09:45:28 2008
