Modified Phenylalanine Dehydrogenase

A modified phenylalanine dehydrogenase,

• comprising one or more mutations of an amino acid residue selected from the group consisting of:
• R2, R10, Y11, C19, L41, G42, G43, C44, A50, S51, M66, C70, F77, K90, Y112, T115, D116, F124, R129, L137, K139, S140, K144, T147, K173, C200, C210, K216, K220, Q222, N227, R228, C234, C240, R255, C256, L257, N264, R271, Q277, K278, R279, S280, C282, N290, G293, L294, Q296, V297, R326, K328, N329, N331, C335, R340, K347, K348, and combinations thereof;
• wherein said phenylalanine dehydrogenase comprises:
• (A) the amino acid sequence of SEQ ID NO:1,
• (B) an amino acid sequence comprising substitution, deletion, insertion, or addition of one or several amino acid residues in the amino acid sequence of SEQ ID NO:1, or
• (C) an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO:1,
• wherein said modified phenylalanine dehydrogenase has a phenylalanine dehydrogenase activity, and
• wherein said modified phenylalanine dehydrogenase has an improved characteristic selected from the group consisting of substrate specificity, solubility, phenylalanine dehydrogenase activity, and combinations thereof.