Degradation of phenolic compounds by the yeast Candida tropicalis HP 15. II. Some properties of the first two enzymes of the degradation pathway.

The first two enzymes of the phenol degradation pathway were determined and characterized in crude extracts from Candida tropicalis HP 15. The phenol hydroxylase (EC 1.14.13.7) was a stable NADPH2- and FAD-dependent enzyme with a pH-optimum of 7.6 to 8.0 and a broad substrate specificity. Influence of ultrasound rapidly reduced the enzyme activity. The catechol 1,2-oxygenase (EC 1.13.1.1) had a broad pH-optimum between 7.5 and 9.6 and a limited substrate specificity. Two active protein bands indicating the presence of two isofunctional enzymes were detectable after electrophoretic separation of crude and partially purified extracts on polyacrylamide gels and specific staining for catechol 1,2-oxygenase activity.