Arginase of Bacillus brevis Nagano: purification, properties, and implication in gramicidin S biosynthesis.

An arginase [EC 3.5.3.1] was purified to homogeneous state from a gramicidin S-producing Bacillus brevis Nagano. The enzyme has a molecular weight of about 180,000 on gel filtration. The subunit molecular weight is 32,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, indicating that the enzyme is hexameric. The optimum pH is found near 10.0. Mn2+ is essential for its activity and Fe2+, Co2+, Ni2+, and Mg2+ cannot replace Mn2+. The enzyme is highly specific for L-arginine with a K(m) value of 12.8 mM for L-arginine, which is similar to that of liver-type arginase in ureotelic animals. B. brevis arginase is apparently induced by the addition of L-arginine to the glutamate medium. The increased formation of L-ornithine, a constituent amino acid of gramicidin S, by arginase may be involved in the accelerated production of gramicidin S by B. brevis in the presence of L-arginine in the growth medium.

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 purified to a homogeneous state from a gramicidin S-producing strain of Bacillus brevis. The enzyme had a molecular weight of about 93,000 and consisted of two identical subunits, each with a molecular weight of about 47,000. One pyridoxal phosphate is bound per subunit. In addition to branched chain amino acids, the enzyme uses L-phenylalanine and L-tryptophan 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.