Characterization of a novel alkaline Arxula adeninivorans urate oxidase expressed in Escherichia coli and its application in reducing uric acid content of food

Abstract

This study reported a novel highly active alkaline urate oxidase (UOX) and demonstrated its application in reducing uric acid content of food under alkaline conditions. The UOX gene was cloned from Arxula adeninivorans NBRC 10858, and its N-terminally his₆-tagged form (rUOX) was overexpressed in Escherichia coli. The rUOX displayed maximal activity at 40 °C and pH 10, kept more than 90% initial activity under alkaline conditions (pH 9-11) and more than 80% at temperatures below 55 °C. The apparent K_m, turnover number (k_cat) and catalytic efficiency (k_cat/K_m) values for the substrate uric acid were respective 29.15 µM, 151.16 s^-1 and 5.19 s^-1. μM^-1, which are improvements over previously reported UOXs. The rUOX efficiently reduced uric acid and purine contents in beer, beef and yeast extract at pH 10, indicating a promising application in food with low purine and uric acid contents to prevent hyperuricemia and gout.

Keywords: Alkaline; Arxula adeninivorans; Gout; Hyperuricemia; Low purine food; Urate oxidase; Uric acid.