Purification, biochemical characterization and structural analysis of uricase produced from a new strain of...

The isolate A85 was identified as Streptomyces enissocaesilis, and it might serve as a novel actinobacteria source for uricase production. The uricase was successfully produced and purified from this novel strain, demonstrating that it could be an efficient source for future applications. Characterization studies of the purified enzyme showed maximal activity at pH 9 and 37 °C. From the differential scanning calorimetry, a melting point of 55.6 °C was observed, which ensured that the purified uricase is thermostable. Overall, 32 fold purification with a 48% yield of uricase was recovered at the end of purification steps. Inhibitor studies revealed that the purified uricase is metalloprotease. V_max and K_m values were found to be 30.39 U/mL and 0.0212 mM, respectively. The molecular mass of the purified uricase was found to be around 32 KDa. Further MALDI-TOF MS analysis identified four peptides as uricase, with a significant score. The purified enzyme was classified as an uricase based on a comprehensive analysis that integrated its amino acid sequence and conserved regions. The secondary structure of the purified uricase using PDBsum revealed 1 beta sheet, 1 beta hairpin, 1 beta bulge, 2 strands, and 2 beta turns. The 3D structure of the purified uricase was predicted through homology modeling, and the structure was validated using Ramachandran plot analysis. Docking results revealed significant binding affinity of -4.3 kcal/mol, which indicates strong and stable interaction of uricase and uric acid substrate.