Abstract: The present invention provides a unit and a method useful for more precise phenylalanine measurement. More specifically, the present invention provides a modified phenylalanine dehydrogenase that includes a mutation of at least one amino acid residue so as to improve the characteristics (for example, substrate specificity, solubility, and phenylalanine dehydrogenase activity) of a phenylalanine dehydrogenase related to measurement of phenylalanine, a method for analyzing phenylalanine by measuring phenylalanine contained in a test sample using the modified phenylalanine dehydrogenase, and others.

Abstract: A mutated tryptophan oxidase suitable for practical implementation is described herein. Specifically, a mutated tryptophan oxidase wherein at least one amino acid residue of a wild-type tryptophan oxidase is mutated and, as a result, has higher tryptophan oxidase activity and/or stability as compared to the wild-type tryptophan oxidase. The mutated tryptophan oxidase can be derived from a wild-type tryptophan oxidase having at least one of Motifs (2), (3), (5), (7), (9), (11), (13), and (14), and at least one amino acid residue in any of these motifs can have mutation. The mutated tryptophan oxidase also can have a mutation of one or more amino acid residues in an amino acid sequence represented by SEQ ID NO: 2 and a sequence homologous thereto.

Abstract: A mutated tryptophan oxidase suitable for practical implementation is described herein. Specifically, a mutated tryptophan oxidase wherein at least one amino acid residue of a wild-type tryptophan oxidase is mutated and, as a result, has higher tryptophan oxidase activity and/or stability as compared to the wild-type tryptophan oxidase. The mutated tryptophan oxidase can be derived from a wild-type tryptophan oxidase having at least one of Motifs (2), (3), (5), (7), (9), (11), (13), and (14), and at least one amino acid residue in any of these motifs can have mutation. The mutated tryptophan oxidase also can have a mutation of one or more amino acid residues in an amino acid sequence represented by SEQ ID NO: 2 and a sequence homologous thereto.