Genetically modified proteins with uricolytic activity are described. Proteins comprising truncated urate oxidases and methods for producing them, including PEGylated proteins comprising truncated urate oxidase are described.

An MXene or a derivative thereof, on which nitrous oxide reductase is immobilized, wherein the MXene has a formula of M.sub.n+1X.sub.nT.sub.s, wherein M is a transition metal of Groups 3, 4, 5, 6, or a combination thereof, of the Periodic Table of the Elements, X is carbon, nitrogen, or a combination thereof, T is oxide, epoxide, hydroxide, C1-C5 alkoxide, fluoride, chloride, bromide, iodide, or a combination thereof, and n is 1, 2, or 3, and s is 0, 1, or 2.