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.