Abstract: Objective To discuss the character of candida utilis uricase and bacillus fastidious intracellular uricase. Methods The new strains were recovered and cultivated to prepare the uricase. Then the uricase was purified by ammonium sulfate fractionation precipitation、DEAE-cellulose 52 chromatography and preparative PAGE. The activity、characterization and subunit constitution were determined with the purified uricase. Results The two uricases were the iso-tetramer. The single peptide chain molecular weight and total molecular weight of candida utilis uricase were 33.0 ku and 134.0 ku individually, the optimum pH was close to 8.8 and more than 50% activity was reserved at pH 7.4, the Michaelis-Menten constant was (32.8±3.1) μmol/L (n=10) and the inhibition constant of xanthine was (4.8±0.2) μmol/L (n=3) for this uricase. For bacillus fastidious intracellular uricase ,its single peptide chain molecular weight and total molecular weight were 35.7 ku and 151.0 ku, the optimum pH exceeded 9.0 and less than 30% activity at pH 7.4 ,the Michaelis-Menten constant and the inhibition constant of xanthine were (204 ± 14)μmol/L (n=8) and (41±7)μmol/L (n=5) individually for it. Conclusion Through the research, a significant theoretical basis was formed for constructing hybrid medicinal uricase to treat diseases associated with hyperuricemia.

Key words: Candida utilis uricase, Bacillus fastidious intracellular uricase, Hyperuricemia