|
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) |
Activity |
2.6.1.42 |
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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