Embodiments of the present disclosure relate to stabilized lactate oxidase compositions, and electrodes, sensors and systems that include the same. Also provided are methods for making the compositions and for detecting and/or measuring lactate in vivo with stable lactate enzyme compositions.

Disclosed herein is directed to a lactate oxidase variant that exhibits reduced affinity to lactate as compared to a wild-type lactate oxidase. The lactate oxidase variant has one or more amino acid substitutions occurring at positions 95, 96, and/or 175 of the wild-type amino acid sequence. Also disclosed herein is a method for detecting and quantifying lactate in various liquid samples by using the present lactate oxidase variant. The method mainly includes steps of contacting the liquid sample with said lactate oxidase variant; measuring a current generated by the reaction between the lactate oxidase variant and the lactate in the liquid sample; and determining the concentration of lactate in the liquid sample by interpolating or extrapolating the current with that of a control sample having a known concentration of lactate.