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B6db references: 97306043

type Journal Article
authors Okada, K.; Hirotsu, K.; Sato, M.; Hayashi, H.; Kagamiyama, H.
title Three-dimensional structure of Escherichia coli branched-chain amino acid aminotransferase at 2.5 A resolution
journal J Biochem (Tokyo)
sel unselected
ui 97306043
year (1997)
volume 121
number 4
pages 637-41.
keywords Alanine Transaminase/chemistry
abstract 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.
last changed 2003/11/18 15:06

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