الفهرس 
Title
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Abstract
Saccharomyces cerevisiae was isolated from an agricultural soil. It was molecularly identified. The obtained PCR sequence was submitted to the NCBI and an accession number was given: MH141315. Extracellular tyrosinase extracted from the yeast Saccharomyces cerevisiae, was purified, characterized and its medicinal applications were assayed. The crude preparation had enzyme activity of 7.99 U/ml and specific activity of 0.84 U/mg. Complete purification protocol was done using (NH4)2SO4 precipitation up to 80 % saturation, gel filtration by sephadex G-100 column chromatography and cation exchange column chromatography using DEAE-cellulose. The final result showed peak of pure tyrosinase with activity of 22.05 U/ml, specific activity of 26.25 U/mg, purification fold of 31.25 and recovery of 22 % of the crude preparation. The molecular mass of the enzyme was found to be approximately 40 KDa using SDS-PAGE. characterization of the pure enzyme indicated that the optimum enzyme concentration of tyrosinase was 4 mg protein/ml, however, optimum substrate (tyrosinase) concentration was 2.2 mM. The km and Vmax values were determined to be 2.56 mg/ml and 20 U/ml, respectively. pH 9 proved to be the optimum value, while 35 {u00B0}Cwas the optimum temperature resulted in maximum enzyme activity