Physiological and Kinetic Studies with Anthranilate Synthetase of Bacillus alvei

Abstract

Anthranilate synthetase from Bacillus alvei was partially purified by ammonium sulfate fractionation and was stabilized by glycerol. The reaction mechanism of the enzyme was found to be sequential with respect to substrate, and the enzyme formed a hydroxamic acid in the absence of Mg ++ . The K m for chorismic acid was 1.25 × 10 −4 m , and the K m for l -glutamine was 5.5 × 10 −4 m . Enzyme activity was inhibited by tryptophan noncompetitively with respect to chorismic acid and uncompetitively with respect to l -glutamine. An analysis of the inhibition patterns indicated that tryptophan may act as a dead end inhibitor and bind at the catalytic site. Enzyme activity could be completely inhibited in vitro and in vivo under the appropriate conditions, and enzyme synthesis was sensitive to repression by tryptophan. A sedimentation coefficient of 5.5 S and an estimated molecular weight of 90,000 were obtained for the enzyme.