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B6db references: 24687296

type Journal Article
authors Uchida Y, Hayashi H, Washio T, Yamasaki R, Kato S, Oikawa T.
title Cloning and characterization of a novel fold-type I branched-chain amino acid aminotransferase from the hyperthermophilic archaeon Thermococcus sp. CKU-1.
journal Extremophiles.
Activity 2.6.1.42
Family 2.6.1.42.b
sel selected
ui 24687296
year (2014 )
 
abstract We successfully cloned a novel branched-chain amino acid aminotransferase (Ts-BcAT; EC 2.6.1.42) gene from the Thermococcus sp. CKU-1 genome and expressed it in the soluble fraction of Escherichia coli Rosetta (DE3) cells. Ts-BcAT is a homodimer with an apparent molecular mass of approximately 92 kDa. The primary structure of Ts-BcAT showed high homology with the fold-type I, subgroup I aminotransferases, but showed little homology with BcATs known to date, i.e., those of Escherichia coli and Salmonella typhimurium, which belong to the fold-type IV, subgroup III aminotransferases. The maximum enzyme activity of Ts-BcAT was detected at 95 C, and Ts-BcAT did not lose any enzyme activity, even after incubation at 90 C for 5 h. Ts-BcAT was active in the pH range from 4.0 to 11.0, the optimum pH was 9.5, and the enzyme was stable between pH 6 and 7. The exceptionally low pK a of the nitrogen atom in the Lys258 ε-amino group in the internal aldimine bond of Ts-BcAT was determined to be 5.52 0.05. Ts-BcAT used 21 natural and unnatural amino acids as a substrate in the overall transamination reaction. L-Leucine and other aliphatic amino acids are efficient substrates, while polar amino acids except glutamate were weak substrates. Phylogenetic analysis revealed that Ts-BcAT is a novel fold-type I, subgroup I branched-chain aminotransferase.
last changed 2014/04/10 14:32

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