Purification and characterization of the tyrosinase ofStreptomyces michiganensis DSM 40015

Tyrosinase of Streptomyces michiganensis DSM 40015 was purified 61-fold from the culture broth: After a fractionated ammonium sulfate precipitation the enzyme was separated by hydrophobic interaction chromatography with Phenyl-Sepharose and ionic interaction chromatography with CM-Cellulose; finally a gel filtration with Sephadex G-75 yielded 1.7% of the originally existent enzyme. SDS gel-electrophoresis of the purified enzyme showed two bands representing a size of 34500 and 32000 dalton, respectively. However, by isoelectric focussing only one band could be found exhibiting an isoelectric point of approximately 9.0. Temperature and pH-optimum of the enzyme activity were 33°C and pH 7.0, respectively. Whereas the enzyme is specific in regard to the aromatic part of its substrate variations of the aliphatic rest are tolerated.