Purification, characterization and medicinal application of tyrosinase extracted from Saccharomyces cerevisiae

Abstract

Extracellular tyrosinase extracted from Saccharomyces cerevisiae was purified, characterized and assayed as medicinal agent. The crude enzyme activity was 7.99 U/ml and specific activity was 0.84 U/mg. The complete purification protocol was done. The final result showed one peak of pure tyrosinase with activity of 1.08 U/ml, specific activity of 2.31 U/mg, purification fold of 31.25 and recovery of 22 %. The molecular mass of the enzyme was approximately 40 KDa. Characterization of the pure enzyme indicated that the optimum enzyme concentration was 4 mg protein/ml, however, optimum substrate [tyrosine] concentration was 2.2 mg/100 ml. The k_m and V_max values were 2.56 mg/ml and 20 U/ml, respectively. PH 9 proved to be the optimum value, while 35 °Cwas the optimum temperature. CuSO₄>MgCl₂>ZnSO₄ enhanced the enzyme activity; however, HgSO₄ completely inhibited it. Assaying the enzyme inhibitors, declared that the metal chelating compound EDTA completely inhibited the enzyme activity which showed clearly that it is a metaloprotein. Medicinal applications of tyrosinase indicated that it exert weak antimicrobial activity against Bacillus subtilis, Pseudomonas aeruginosa, E. coli and Staphylococus aureus, but not have any antifungal activity. The enzyme proved to have antioxidant activity 50% of glutathione peroxidase. It also increased the viability of normal skin melanocyte cell line [MFB-4] before and after UV-irradiation indicated its protective and healing effect against UV-rays. The enzyme also reducing the viability of breast carcinoma cell line [MCF-7] after and before UV exposure declared that it may have anticancer activity