Studies on the Inhibition and Molecular Properties of CrystallinePseudomonasIsoamylase

Pseudomonas isoamylase was inhibited by N-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide, iodine (pH 8), iodoacetate (pH 3.5), phenylmercuriacetate, 2,4-dinitrofluorobenzene, Hg2+ and Ag+. The enzyme was also inhibited by oligosaccharides with α-l,4-glucosidic linkages, and studies on the competitive inhibition by maltotriose showed that the enzyme has a site capable of binding α-l,4-linked glucosyl units. The subunit structure of the enzyme was determined by sedimentation equilibrium analysis and agarose gel filtration. The enzyme appears to be composed of two subunits, each with a molecular weight about 50,000 which are not linked covalently.