Purification and properties of urease fromSporobolomyces roseus

Urease (EC 3.5.1.5) catalyses the hydrolysis of urea to ammonia and carbon dioxide. The enzyme fromSporobolomyces roseus was enriched 780-fold and purified to apparent homogeneity using heat treatment, ion exchange chromatography on Q-Sepharose fast flow, hydrophobic interaction chromatography on Phenyl-Sepharose, size exclusion chromatography on Sephacryl S 300 HR, and ion exchange chromatography on MonoQ. Analysis of the purified enzyme by SDS-PAGE demonstrated the presence of subunits with a molecular weight of 90 (± 4) kDa. The M_r of the native enzyme was estimated by size exclusion chromatography to be 340 (± 30) kDa, suggesting a tetrameric structure different from other ureases isolated so far from both prokaryotes and eukaryotes. The enzyme was heat-stable, showing no loss of activity after incubation at 70 °C for 15 min. The highest urease activities were observed after growth on media containing urea as the sole source of nitrogen.