Patent ID: 7732179

Claim:
An isolated mutant of PQQ-dependent soluble glucose dehydrogenase (s-GDH) that relative to the A. calcoaceticus s-GDH wild-type polypeptide of SEQ ID NO: 2 has improved specificity for glucose as compared to maltose, said mutant comprising an s-GDH polypeptide, said s-GDH polypeptide consisting of an amino acid sequence having at least 90% sequence identity with the A. calcoaceticus s-GDH wild-type sequence of SEQ ID NO: 2, wherein said mutant differs from SEQ ID NO: 2 by a substitution at position 348 of either glycine, alanine or serine; and a) at least one stabilizing mutation selected from the group consisting of D87R; N122K; S124K; S146G; V298L and L386F; b) at least one glucose affinity mutation selected from the group consisting of L110H L110Y; N229A, N229G, N229S, Q246H, Q246M, Q246N, Y333A; G339T, M341V, V349A, V349G and V436P, and optionally; c) one or more glucose specificity mutation(s) selected from the group consisting of Q145P, D163G, D163N, A164F, L169F, Y171G, I208L, I208V, T224I, E245D, G276S, A294D, A294E; V300A, V300S, V300N, V300Y, V300I, T307G, T323V, A354Y, A354E, A354L, R378I, R378M, R378A, R378D, N428P and insertion 429 P; and wherein the mutant has s-GDH activity and the designated positions correspond to the amino acid positions known from the A. calcoaceticus s-GDH wild-type sequence of SEQ ID NO: 2.