Abstract: A method for quantifying a substance, which method includes the steps of: introducing a sample containing a measurement target substance to a biosensor comprising an enzyme electrode comprising an electrode and an oxidoreductase placed on the electrode in a state where direct electron transfer with the electrode occurs, and a counter electrode; applying an AC voltage to the enzyme electrode to carry out impedance measurement; and calculating the substance concentration based on an index obtained by the impedance measurement; is provided.

Abstract: 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.

Abstract: A method for measuring a glycated protein in a sample, the method comprising (1) a step of allowing a sample in which a degradation product has been generated from a glycated protein by a protease to react with an oxidoreductase in the presence of an electron mediator to generate a reduced electron mediator; and (2) a step of detecting the reaction state in the step (1) by an electrochemical technique using an interdigitated electrode.

Abstract: The present invention provides an enzyme electrode composed of a carbon particle on which glucose dehydrogenase (GDH) with flavine adenine dinucleotide (FAD) as a coenzyme is supported and an electrode layer contacting the carbon particle, wherein the carbon particle and/or the electrode layer are/is composed of the carbon particles with a particle diameter of not more than 100 nm and a specific surface area of at least 200 m2/g.

Abstract: The present invention provides an enzyme electrode composed of a carbon particle on which glucose dehydrogenase (GDH) with flavine adenine dinucleotide (FAD) as a coenzyme is supported and an electrode layer contacting the carbon particle, wherein the carbon particle and/or the electrode layer are/is composed of the carbon particles with a particle diameter of not more than 100 nm and a specific surface area of at least 200 m2/g.

Abstract: A measuring method of measuring a concentration of a target ingredient in a sample by using a sensor including an interdigitated array electrode that includes a first electrode and a second electrode, and a reagent layer on the interdigitated array electrode, the measuring method includes: applying a voltage to between the first electrode and the second electrode; measuring a first current value of an electric current flowing between the first electrode and the second electrode; measuring a second current value of the current flowing between the first electrode and the second electrode; calculating the concentration of the target ingredient in the sample, based on a third current value; calculating a correction value, based on the first current value and the second current value; and a step of correcting the concentration of the target ingredient in the sample, based on the correction value.

Abstract: Amino acid mutation(s) can be introduced to Sclerotinia sclerotiorum- or Aspergillus niger-derived glucose dehydrogenase to obtain a glucose dehydrogenase variant with significantly enhanced productivity in E. coli. The glucose dehydrogenase of the present invention is low reactive with xylose.

Abstract: A modified pyrroloquinoline quinone glucose dehydrogenase that exhibits a high selectivity for glucose is provided. A modified pyrroloquinoline quinone glucose dehydrogenase is disclosed in which the amino acid residue G at Position 99 of a pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 1, or the amino acid residue G at Position 100 of the pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 3, is substituted by the amino acid sequence TGZN (where Z is SX, S, or N and X is any amino acid residue). The modified PQQGDH of the present invention may additionally comprise one or more mutations selected from the group consisting of Q192G, Q192A, or Q192S; L193X; E277X; A318X; Y367A, Y367F, or Y367W; G451C; and N452X (where X is any amino acid residue).

Abstract: A fusion protein of pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) and a cytochrome is disclosed. PQQGDH is, for example, a water-soluble PQQGDH derived from Acinetobacter calcoaceticus. The cytochrome is, for example, an electron transfer domain of quinohemoprotein ethanol dehydrogenase from Comamonas testosteroni. The fusion protein of the present invention shows intramolecular electron transfer from PQQ, a redox center, to the cytochrome, which allow construction of a direct electron transfer-type glucose sensor which requires no electron mediators.

Abstract: An aptamer having a G-quartet structure and being at least one selected from the group consisting of the following polynucleotides, the aptamer having a binding ability to an amyloid protein oligomer: (1) a polynucleotide comprising a base sequence represented by any one of SEQ ID NO:1 to SEQ ID NO:18; (2) a polynucleotide comprising a base sequence that includes at least four sets of at least two consecutive guanosine nucleotides and in which one or several bases has been deleted, substituted, or added in a base sequence represented by any one of SEQ ID NO:18; and (3) a polynucleotide that is a multimer including the polynucleotide of (1) or (2) as a structural unit.

Abstract: A glucose dehydrogenase, which is an enzyme that has high substrate specificity, can be produced at a low cost, is not affected by oxygen dissolved in a measurement sample and, in particular, has superior thermal stability is obtained by culturing a microorganism belonging to the genus Burkholderia. A glucose sensor utilizing the glucose dehydrogenase protein is described.

Abstract: Disclosed is a modified glucose dehydrogenases that has dramatically increased productivity in Escherichia coli and dramatically increased thermal stability, which is obtained by introducing specific amino acid mutations to glucose dehydrogenase derived from Botryotinia fuckeliana. Also disclosed is a modified glucose dehydrogenases that has dramatically increased productivity in E. coli and dramatically increased thermal stability, which is obtained by replacing two amino acid residues in glucose dehydrogenase of fungal origin with cysteine residues. The novel glucose dehydrogenase has a low reactivity to xylose.

Abstract: A modified pyrroloquinoline quinone glucose dehydrogenase that exhibits a high selectivity for glucose is provided. A modified pyrroloquinoline quinone glucose dehydrogenase is disclosed in which the amino acid residue G at Position 99 of a pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 1, or the amino acid residue G at Position 100 of the pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 3, is substituted by the amino acid sequence TGZN (where Z is SX, S, or N and X is any amino acid residue). The modified PQQGDH of the present invention may additionally comprise one or more mutations selected from the group consisting of Q192G, Q192A, or Q192S; L193X; E277X; A318X; Y367A, Y367F, or Y367W; G451C; and N452X (where X is any amino acid residue).

Abstract: Amino acid mutation(s) can be introduced to Sclerotinia sclerotiorum- or Aspergillus niger-derived glucose dehydrogenase to obtain a glucose dehydrogenase variant with significantly enhanced productivity in E. coli. The glucose dehydrogenase of the present invention is low reactive with xylose.

Abstract: A modified pyrroloquinoline quinone glucose dehydrogenase that exhibits a high selectivity for glucose is provided. A modified pyrroloquinoline quinone glucose dehydrogenase is disclosed in which the amino acid residue G at Position 99 of a pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 1, or the amino acid residue G at Position 100 of the pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) represented by SEQ ID NO: 3, is substituted by the amino acid sequence TGZN (where Z is SX, S, or N and X is any amino acid residue). The modified PQQGDH of the present invention may additionally comprise one or more mutations selected from the group consisting of Q192G, Q192A, or Q192S; L193X; E277X; A318X; Y367A, Y367F, or Y367W; G451C; and N452X (where X is any amino acid residue).

Abstract: A glucose dehydrogenase, which is an enzyme that has high substrate specificity, can be produced at a low cost, is not affected by oxygen dissolved in a measurement sample and, in particular, has superior thermal stability is obtained by culturing a microorganism belonging to the genus Burkholderia. A glucose sensor utilizing the glucose dehydrogenase protein is described.

Abstract: In one form, a fructosyl peptidyl oxidase derived from a budding yeast Phaeosphaeria nodorum for assaying a glycated protein in a sample is provided. The fructosyl peptidyl oxidase has higher activity toward fructosyl valine as well as fructosyl valyl histidine, and may be useful in assaying HbA1c with higher sensitivity and specificity. Still, other forms include unique methods, techniques, systems and devices involving a fructosyl peptidyl oxidase.

Abstract: A glucose dehydrogenase, having high substrate specificity, can be produced at a low cost, is not affected by oxygen dissolved in a measurement sample and, in particular, has superior thermal stability is obtained by culturing a microorganism belonging to the genus Burkholderia, particularly Burkholderia cepacia. The glucose dehydrogenase produced by the microorganism is collected from the medium and/or from the cells of the microorganism.

Abstract: A glucose dehydrogenase, having high substrate specificity, can be produced at a low cost, is not affected by oxygen dissolved in a measurement sample and, in particular, has superior thermal stability is obtained by culturing a microorganism belonging to the genus Burkholderia, particularly Burkholderia cepacia. The glucose dehydrogenase produced by the microorganism is collected from the medium and/or from the cells of the microorganism.

Abstract: An aptamer having a G-quartet structure and being at least one selected from the group consisting of the following polynucleotides, the aptamer having a binding ability to an amyloid protein oligomer: (1) a polynucleotide comprising a base sequence represented by any one of SEQ ID NO:1 to SEQ ID NO:18; (2) a polynucleotide comprising a base sequence that includes at least four sets of at least two consecutive guanosine nucleotides and in which one or several bases has been deleted, substituted, or added in a base sequence represented by any one of SEQ ID NO:18; and (3) a polynucleotide that is a multimer including the polynucleotide of (1) or (2) as a structural unit.