Zwitterionic modification strategy enhances the stability of uricase

To address the issues of low enzymatic activity, poor solubility, and inadequate stability of mammalian-derived uricase, this study utilized the superhydrophilic zwitterionic peptide chain polyglutamic acid-lysine （pEK） for modification. By employing a microbial expression system, pEK peptide chains of varying lengths were fused to the C-terminus of uricase for co-expression. The results demonstrated that modification with pEK₆₀, composed of 60 EK repeat sequences, increased the solubility of uricase more than 60-fold, enhanced enzymatic activity 4.4-fold, and improved catalytic efficiency （K_cat/K_m） 2.1-fold. Additionally, the long-term stability of the modified uricase in solution and the retention of enzymatic activity after lyophilization were significantly improved. These findings lay a foundation for subsequent pharmaceutical modification research on mammalian-derived uricase.