Recombinantly expressed glutamate oxidase

A glutamate oxidase mutant comprising an amino acid substitution, wherein

• the thermal stability of the glutamate oxidase mutant after the amino acid substitution is improved compared to the glutamate oxidase before the substitution, and
• the glutamate oxidase mutant meets a condition selected from the group consisting of the following:
• (i) when the amino acid sequence of the glutamate oxidase mutant is aligned with the amino acid sequence of SEQ ID NO:
• 1, the glutamate oxidase mutant comprises a substitution of the amino acid at the position corresponding to a position selected from the group consisting of the 87th, 103rd, 133rd, 186th, 297th, 376th, 393rd, 428th, 516th, 566th, 568th, 585th, and 615th positions of SEQ ID NO:
• 1,
• (ii) the glutamate oxidase mutant of said (i), wherein the glutamate oxidase mutant consists of an amino acid sequence comprising a substitution, deletion or addition of one or several amino acids at a position other than the positions corresponding to the 87th, 103rd, 133rd, 186th, 297th, 376th, 393rd, 428th, 516th, 566th, 568th, 585th, and 615th positions of SEQ ID NO:
• 1,
• (iii) with regard to the glutamate oxidase mutant of said (i) or (ii), the full length amino acid sequence thereof comprises an amino acid sequence identity of 70% or more, 80% or more, or 90% or more with the amino acid sequence of SEQ ID NO:
• 1 or SEQ ID NO:
• 58, and
• (iv) with regard to the glutamate oxidase mutant of said (i) or (ii), the full length amino acid sequence thereof comprises an amino acid sequence identity of 70% or more, 80% or more, or 90% or more with the amino acid sequence of SEQ ID NO:
• 1 or SEQ ID NO:
• 58, the amino acid substitution at the position corresponding to the 291st position of SEQ ID NO:
• 1 in the glutamate oxidase mutant is arginine, and the amino acid sequence of the positions corresponding to the 51st to 56th positions of SEQ ID NO:
• 1 is Gly-Xaa-Gly-Xaa-Xaa-Gly wherein Xaa represents any amino acid.