PURIFICATION AND PROPERTIES OF BRANCHED-CHAIN AMINO-ACID AMINOTRANSFERASE FROM GRAMICIDIN S-PRODUCING BACILLUS-BREVIS

The branched chain amino acid aminotransferase [EC 2.6.1.42] was purif ied to a homogeneous state from a gramicidin S-producing strain of Bac illus brevis. The enzyme had a molecular weight of about 93,000 and co nsisted of two identical subunits, each with a molecular weight of abo ut 47,000. One pyridoxal phosphate is bound per subunit. In addition t o branched chain amino acids, the enzyme uses L-phenylalanine and L-tr yptophan as the amino donor, indicating that B. brevis branched chain amino acid aminotransferase has a broad substrate specificity for the amino donor. The enzyme utilized 2-oxoglutarate as the amino acceptor. The purified enzyme exhibits its absorption maxima at 332 and 427 nm at neutral pH.