Branched chain aminotransferase

Xian, M., Alaux, S., Sagot, E. and Gefflaut, T., Chemoenz3fmatic synthesis of glutamic acid analogues substrate specificity and S3mthetic apphcations of branched chain aminotransferase from Escherichia coli. J. Org. Chem., 2007, 72, 7560-7566. 

Branched chain aminotransferase Gamma-aminobutyrate aminotransferase CO-Amino acid pyruvate aminotransferase Tyrosine aminotransferase Serine pyruvate aminotransferase... 

Branched-chain aminotransferases (BCATs) evolved from aspartate aminotransferases (AATs) showed a record 105- to 2 x 106-fold improvement in catalytic efficiency (kcat/KM). Not only were the 13-17 amino acid substitutions concentrated in the most active mutants, but all but one mutated amino acid residues are located far from the active site. With directed evolution, enantioselectivities can be improved on enantiounspecific enzymes (from E = 1.1 to 25.8) and even inverted to yield the opposite enantiomer in comparison to the wild type (40% d- to both 90% d- and 20% L-). 

The aminotransferase class of enzymes (E.C. 2.6.1.x), also known as transaminases, are ubiquitous, PLP-requiring enzymes that have been used extensively to prepare natural L-amino acids and other chiral compounds.30 123 124 The L-aminotransferases catalyze the general reaction shown in Scheme 19.19 where an amino group from one L-amino acid is transferred to an a-keto acid to produce a new L-amino acid and the respective a-keto acid (see also Chapter 3). Those enzymes most commonly used as industrial biocatalysts have been cloned, overexpressed, and generally used as whole-cell or immobilized preparations. These include branched chain aminotransferase (BCAT) (E.C. 2.6.1.42), aspartate aminotransferase (AAT) (E.C. 2.6.1.1), and tyrosine aminotransferase (TAT) (E.C. 2.6.1.5). 

Wu JY, Kao HJ, Li SC, Stevens R, Hillman S, Millington D, Chen YT. ENU mutagenesis identifies mice with mitochondrial branched-chain aminotransferase deficiency resembling human maple syrup urine disease. J. Clin. Invest. 2004 113 434 440. 

Bondar, D.C., et al. (2005) Involvement of a branched-chain aminotransferase in production of volatile sulfur compounds in Yarrowia lipolytica. Appl. Environ. Microbiol. 71, 4585-4591... 

Figure 14.2. Example of some metabolic pathways adopted by Lactobacillus plantarum during fermentation of vegetable and fruit juices. He, isoleucine Leu, leucine Val, valine His, histidine Glu, glutamic acid BcAT, branched-chain aminotransferase KDC, a-keto acid decarboxylase ADH, alcohol dehydrogenase MLE, malol-actlc enzyme HDC, histidine decarboxylase (Adapted from Filannino etal. 2014)...

L. Lactis (84 strains) AA converting activity (cell extracts from cells grown in 2 media) Activity of branched chain aminotransferase (BcaT), alpha-hydroxyisocaproic acid dehydrogenase (HicDH), and esterase individual strains showed va-y diverse regulatory responses, with the activities in the 2 media in general poorly correlated (Bachmann et al. 2009)... 

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