On the properties of some aromatic ring-opening enzymes of species of the genus Nocardia

Oxidase enzymes which open the aromatic ring of either protocatechuic acid or catechol have been induced by growth of Nocardia spp. on nitrobenzoic acids. Some of their properties are described. No cofactor or metal requirements have been found for a purified, protocatechuic acid oxidase from N. erythropolis but, unlike the corresponding enzymes from Neurospora and Pseudomonas, the enzyme exhibits a marked activity optimum at pH 7.5. Catechol oxidase activity in N. opaca is very similar in properties to that of Pseudomonas but crude extracts prepared by ultrasonic disintegration accumulate cis-cis-muconic acid which has only previously been found by using a purified preparation. Tentative evidence for a lactonic type comound between β-carboxymuconic acid and β-oxoadipic acid in extracts of N. crythropolis is presented.