1A3G

BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE FROM ESCHERICHIA COLI

Summary for 1A3G

• Entry DOI: 10.2210/pdb1a3g/pdb
• Descriptor: BRANCHED-CHAIN AMINO ACID AMINOTRANSFERASE, PYRIDOXAL-5'-PHOSPHATE (3 entities in total)
• Functional Keywords: aminotransferase, pyridoxal enzyme
• Biological source: Escherichia coli
• Total number of polymer chains: 3
• Total formula weight: 102742.58

Authors

Okada, K.,Hirotsu, K.,Sato, M.,Hayashi, H.,Kagamiyama, H. (deposition date: 1998-01-21, release date: 1998-05-27, Last modification date: 2024-06-05)

Primary citation

Okada, K.,Hirotsu, K.,Sato, M.,Hayashi, H.,Kagamiyama, H.
Three-dimensional structure of Escherichia coli branched-chain amino acid aminotransferase at 2.5 A resolution.
J.Biochem.(Tokyo), 121:637-641, 1997

PubMed 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.

PubMed: 9163511

Experimental method

X-RAY DIFFRACTION (2.5 Å)