Abstract: Engineered D-?-hydroxybutyrate dehydrogenases (BHBDhs) are disclosed. In some embodiments, the BHBDhs are derived from enzymes which are putative homologues of A. faecalis-derived BHBDh, including from thermophilic bacteria and radiation-resistance bacteria. These BHBDhs may also comprise additional mutations to increase their catalytic activity. Further, BHBDhs modified to include an NAD-binding loop, so as to tightly bind an NAD+ co-factor, are also disclosed.

Abstract: Compositions, devices, kits and methods are disclosed for assaying lactate with an engineered lactate oxidoreductase. The engineered lactate oxidoreductase has increased stability.

Abstract: A method for quantifying a target substance, comprising: bringing a sample containing the target substance into contact with a biosensor which comprises an enzyme electrode containing an oxidoreductase and a counter electrode; measuring a change in the potential difference between the enzyme electrode and the counter electrode due to oxidation reaction of the target substance catalyzed by the oxidoreductase; and calculating the concentration of the target substance based on the change in the potential difference; wherein a potential is applied between the enzyme electrode and the counter electrode before the measurement of the change in the potential difference.

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: A method for quantifying a target substance, comprising: bringing a sample containing the target substance into contact with a biosensor which comprises an enzyme electrode containing an oxidoreductase and a counter electrode; measuring a change in the potential difference between the enzyme electrode and the counter electrode due to oxidation reaction of the target substance catalyzed by the oxidoreductase; and calculating the concentration of the target substance based on the change in the potential difference; wherein a potential is applied between the enzyme electrode and the counter electrode before the measurement of the change in the potential difference.

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: The present invention provides a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

Abstract: The present invention provides a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

Abstract: The present invention provides a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

Abstract: The present invention provides a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

Abstract: The present invention provides a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

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 a method for measuring a substrate concentration by accumulating an energy resulting from a reaction between a biocatalyst and a substrate recognized by the biocatalyst to a certain level; and using a dependency of an accumulation rate on the substrate concentration as an index; and a apparatus therefor. In particular, the present invention provides a method in which the measurement of the accumulation rate is carried out by measuring a frequency of an energy release in a certain amount of time when the energy accumulated in the capacitor reaches the certain level and is then released.

Abstract: A high sensitivity electrochemistry type method for measuring adenine nucleotide which has a convenient and further miniaturized measuring device structure; is low in consumptive power; and does not require a treatment operation for substances that cause turbidity is provided. A method for measuring adenine nucleotide, which comprises a step A for converting adenosine triphosphate to adenosine diphosphate by an enzyme E1, a step B for converting said adenosine diphosphate and a phosphate donor P2 to adenosine triphosphate and dephosphorylated phosphate donor P2? by an enzyme E2, and a step C for electrochemically measuring said donor P2? by carrying out an oxidation-reduction reaction.