An organic solvent resistant tyrosinase from Streptomyces sp. REN-21: purification and characterization

We found a tyrosinase, which has high activity in the presence of organic solvents, in the culture filtrate of Streptomyces sp. REN-21. The organic solvent resistant tyrosinase (OSRT) was purified from the culture filtrate by three column chromatographies. About 1.2 mg of purified OSRT was obtained from 5.6 liters of the culture filtrate with a yield of 26.0%. The purified enzyme had a single polypeptide chain with a molecular mass of about 32,000 Da. The optimum pH and temperature of OSRT were pH 7.0 and 35 degrees C using L-beta-(3,4-dihydroxyphenyl)alanine (L-DOPA) as substrate. OSRT showed stereospecificity toward L-, DL-, and D-enantiomers of DOPA or tyrosine. OSRT had 44% of the activity of the control even in the presence of 50% ethanol, while a mushroom tyrosinase showed only 6% activity under the same conditions. Moreover, OSRT retained its original activity even after 20 h of incubation at 30 degrees C in the presence of 30% ethanol.