Purification and characterization of two muconate cycloisomerase isozymes from aniline-assimilating Frateuria species ANA-18.

Two muconate cycloisomerases (MC I and MC II, EC 5.5.1.1) were purified to homogeneity from an aniline-grown Frateuria sp. ANA-18. MC I and MC II were similar in molecular mass, optimal pH, and pH stability but different in thermostability, and some other enzymatic properties. NH2-terminal amino acid sequences were different between the two isozymes, indicated that these are encoded by different genes. Different inducible production of MC I and MC II suggested that two catechol branches involved in the beta-ketoadipate pathway function in Frateuria sp. ANA-18.