Abstract: The present invention pertains to an enzymatic measurement method using an antibody-enzyme complex or a nucleic acid probe measurement method using an enzyme-labeled nucleic acid probe, in both of which the quantification of a product of a reaction by an enzyme in the antibody-enzyme complex or the enzyme-labeled nucleic acid probe is performed by generating thio-NAD(P)H by an enzymatic cycling reaction using NAD(P)H, thio-NAD(P), and a dehydrogenase (DH), and measuring the amount of the generated thio-NAD(P)H or measuring a change in color caused by the generated thio-NAD(P)H. An enzymatic reaction system in which NAD(P) generated from NAD(P)H by the enzymatic cycling reaction is selectively reduced, is caused to coexist with the enzymatic cycling reaction. The present invention also pertains to a kit for enzyme immunoassay, and a kit for nucleic acid probe measurement.

Abstract: Provided is a ultra-high-sensitivity assay in which the assay can be made on a commonly used assay apparatus such as an absorptiometer and a plate reader or with naked eyes. The high-sensitivity assay in which the assay can be made on a commonly used assay apparatus or with naked eyes can be provided by combining an enzyme cycling method using thio-NAD(P) as a coenzyme, a labeling enzyme and a substrate for the labeling enzyme optimally, and by amplifying thio-NAD(P)H, which is a signaling substance, exponentially and then quantifying the thio-NAD(P)H colorimetrically.

Abstract: The present invention pertains to an enzymatic measurement method using an antibody-enzyme complex or a nucleic acid probe measurement method using an enzyme-labeled nucleic acid probe, in both of which the quantification of a product of a reaction by an enzyme in the antibody-enzyme complex or the enzyme-labeled nucleic acid probe is performed by generating thio-NAD(P)H by an enzymatic cycling reaction using NAD(P)H, thio-NAD(P), and a dehydrogenase (DH), and measuring the amount of the generated thio-NAD(P)H or measuring a change in color caused by the generated thio-NAD(P)H. An enzymatic reaction system in which NAD(P) generated from NAD(P)H by the enzymatic cycling reaction is selectively reduced, is caused to coexist with the enzymatic cycling reaction. The present invention also pertains to a kit for enzyme immunoassay, and a kit for nucleic acid probe measurement.

Abstract: Provided is a ultra-high-sensitivity assay in which the assay can be made on a commonly used assay apparatus such as an absorptiometer and a plate reader or with naked eyes. The high-sensitivity assay in which the assay can be made on a commonly used assay apparatus or with naked eyes can be provided by combining an enzyme cycling method using thio-NAD(P) as a coenzyme, a labeling enzyme and a substrate for the labeling enzyme optimally, and by amplifying thio-NAD(P)H, which is a signaling substance, exponentially and then quantifying the thio-NAD(P)H colorimetrically.