Urate oxidase is considered as an important therapeutic
enzyme used to control
hyperuricemia. In spite of widespread distribution in numerous (micro)organisms, active
urate oxidase is absent in higher primates (humans and apes) due to gene mutations. Considering the therapeutic significance of
urate oxidase, further understanding on the inactivation process of the
enzyme during primate evolution is critical. This study, therefore, aims to express genetically modified human
urate oxidase in the methylotrophic yeast Pichia pastoris. Accordingly, the genetically modified human
urate oxidase was successfully expressed intracellularly and extracellularly under the control of an
alcohol oxidase promoter and was subjected to the
enzyme activity assay. The results demonstrated that reactivating the non-functional human
urate oxidase gene fully or even moderately by simply replacing the
premature stop codons is impossible. This finding confirms the idea that a number of successive loss-of-function missense mutations occurred during evolution, making higher primates functional
uricase-deficit and vulnerable to hyperuricemic disorders.