Proteolysis-resistant extracellular uricase from the sponge-derived Streptomyces rochei

This study aimed to identify proteolysis-resistant extracellular uricase by screening three hundred marine microorganisms, including bacteria, actinobacteria and filamentous fungi. The isolate, demonstrating resistance to proteolysis and producing extracellular uricase with relatively high activity was identified as Streptomyces rochei 6SM85. The enzyme was purified approximately 3.6 fold, yielding 1.23%, using ion exchange chromatography. The molecular weight of the purified uricase was estimated to be approximately 14 kDa by SDS-PAGE. The optimum temperature and pH for uricase were determined to be 35 °C and 8–9, respectively. It was demonstrated that uricase retained up to 46% of its activity after half an hour at 40 °C and exhibited higher activity at neutral and basic pH compared to acidic pH. Its activity increased in the presence of 1 mM Mg2+, Na+, and EDTA, while it decreased by 86% in the presence of Cu2+. This study represents the first report on the production and characterization of extracellular proteolysis-resistant uricase from marine-derived Streptomyces.