A mutant cytochrome protein originated from a cytochrome protein having three heme-binding domains, which mutant cytochrome protein lacks the first heme-binding domain and the second heme-binding domain as counted from the N-terminus, is provided. The mutant cytochrome protein may lack a region(s) containing the first and second heme-binding domains.

In some embodiments, the present invention provides a protein comprising amino acids in the following sequence L(X).sub.n=14X.sup.3(X).sub.n=1X.sup.1(X).sub.n=1E(X).sub.n=4P(X).sub.n=1NR(X).sub.n=3S(X).sub.n=4D(X).sub.n=2G(X).sub.n=7Y(X).sub.n=4Y (X).sub.n=32-34X.sup.2, wherein each X independently represents any naturally occurring amino acid residue and n indicates the number of amino acid residues represented by the respective parenthetical at that position, wherein: a) X1 is selected from the group consisting of S, C, T, M, V, Y, N, P, L, G, Q, A, I, D, W, H, or E, wherein if X.sup.1 is L, H or V, then X.sup.3 is D; and/or b) X.sup.2 is selected from the group consisting of H, L, S or V. In some embodiments, the present invention also provides a protein comprising amino acids in the sequence set forth by SEQ ID NO: 38 or SEQ ID NO: 39, except that: the amino acid at position 406 is an amino acid other than F; and/or the amino acid at position 474 is an amino acid other than N.

A flavin-conjugated glucose dehydrogenase which is composed of proteins having the following amino acid sequence (a), (b) or (c), and having glucose dehydrogenase activity: (a) an amino acid sequence represented by SEQ ID NO: 2, 3, 5, 6, 8 or 9; (b) an amino acid sequence in which one or more amino acids are deleted from, replaced in or added to the amino acid sequence represented by SEQ ID NO: 2, 3, 5, 6, 8 or 9; (c) an amino acid sequence having at least 85% identity with the amino acid sequence represented by SEQ ID NO 2 or 3, at least 95% identity with the amino acid sequence represented by SEQ ID NO 5 or 6, or at least 80% identity with the amino acid sequence represented by SEQ ID NO 8 or 9.

A biosensor comprises an amino acid sequence of an enzyme such as glucose dehydrogenase which is capable of reacting with a substrate to produce one or more electrons, wherein the enzyme has been engineered to be switchable from a catalytically inactive to a catalytically active state in response to binding a target molecule. A method of detecting a target molecule is provided wherein an enzyme such as glucose dehydrogenase reacts with a substrate to produce one or more electrons as a result of the enzyme switching from a catalytically inactive to a catalytically active state in response to binding the target molecule.

An object of the present invention is to provide: a novel gene (polynucleotide) encoding an FAD-conjugated glucose dehydrogenase having excellent properties that it has excellent reactivity to glucose, excellent thermal stability, and excellent substrate-recognition performance and also has a low activity for maltose; a process for the production of the enzyme using a transformant cell transfected with the gene; and a method for the determination of glucose, a reagent composition for use in the determination of glucose, a biosensor for use in the determination of glucose and others, each characterized by using the enzyme obtained. The invention relates to a polynucleotide encoding an FAD-conjugated glucose dehydrogenase, comprising a polypeptide containing an amino acid sequence: X1-X2-X3-X4-X5-X6 (wherein X1 and X2 independently represent an aliphatic amino acid residue; X3 and X6 independently represent a branched amino acid residue; and X4 and X5 independently represent a heterocyclic amino acid residue or an aromatic amino acid residue); and others.

An object of the present invention is to provide: a novel gene (polynucleotide) encoding an FAD-conjugated glucose dehydrogenase having excellent properties that it has excellent reactivity to glucose, excellent thermal stability, and excellent substrate-recognition performance and also has a low activity for maltose; a process for the production of the enzyme using a transformant cell transfected with the gene; and a method for the determination of glucose, a reagent composition for use in the determination of glucose, a biosensor for use in the determination of glucose and others, each characterized by using the enzyme obtained. The invention relates to a polynucleotide encoding an FAD-conjugated glucose dehydrogenase, comprising a polypeptide containing an amino acid sequence: X1-X2-X3-X4-X5-X6 (wherein X1 and X2 independently represent an aliphatic amino acid residue; X3 and X6 independently represent a branched amino acid residue; and X4 and X5 independently represent a heterocyclic amino acid residue or an aromatic amino acid residue); and others.

The present invention provides members that produce on a large scale a coenzyme-linked glucose dehydrogenase which has excellent substrate-recognizing ability toward glucose while providing low action on maltose. The present invention relates to a polynucleotide encoding a soluble coenzyme-linked glucose dehydrogenase that catalyzes the oxidation of glucose in the presence of an electron acceptor and has an activity toward maltose of 5% or lower; a polypeptide encoded by the nucleotide sequence of the polynucleotide; a recombinant vector carrying the polynucleotide; a transformed cell produced using the recombinant vector; a method for producing a polypeptide comprising culturing the transformed cell and collecting from the cultivated products a polypeptide that links to FAD to exert the glucose dehydration activity; a method for determination of glucose using the polypeptide; a reagent composition for determination of glucose; and a biosensor.

An object of the present invention is to construct a more excellent glucose sensor, and to provide GDH more suitable for the glucose sensor. Provided is FAD-dependent glucose dehydrogenase in which the range of molecular weight distribution observed by SDS-PAGE is within 50 kDa when viewed in a molecular weight distribution in which the relative value of band intensity exceeds 60% of the maximum value.

An object of the present invention is to provide: a novel gene (polynucleotide) encoding an FAD-conjugated glucose dehydrogenase having excellent properties that it has excellent reactivity to glucose, excellent thermal stability, and excellent substrate-recognition performance and also has a low activity for maltose; a process for the production of the enzyme using a transformant cell transfected with the gene; and a method for the determination of glucose, a reagent composition for use in the determination of glucose, a biosensor for use in the determination of glucose and others, each characterized by using the enzyme obtained. The invention relates to a polynucleotide encoding an FAD-conjugated glucose dehydrogenase, comprising a polypeptide containing an amino acid sequence: X1-X2-X3-X4-X5-X6 (wherein X1 and X2 independently represent an aliphatic amino acid residue; X3 and X6 independently represent a branched amino acid residue; and X4 and X5 independently represent a heterocyclic amino acid residue or an aromatic amino acid residue); and others.

An object of the present invention is to provide: a novel gene (polynucleotide) encoding an FAD-conjugated glucose dehydrogenase having excellent properties that it has excellent reactivity to glucose, excellent thermal stability, and excellent substrate-recognition performance and also has a low activity for maltose; a process for the production of the enzyme using a transformant cell transfected with the gene; and a method for the determination of glucose, a reagent composition for use in the determination of glucose, a biosensor for use in the determination of glucose and others, each characterized by using the enzyme obtained. The invention relates to a polynucleotide encoding an FAD-conjugated glucose dehydrogenase, comprising a polypeptide containing an amino acid sequence: X1-X2-X3-X4-X5-X6 (wherein X1 and X2 independently represent an aliphatic amino acid residue; X3 and X6 independently represent a branched amino acid residue; and X4 and X5 independently represent a heterocyclic amino acid residue or an aromatic amino acid residue); and others.