Analytical Sciences

Abstract − Analytical Sciences, 37(10), 1469 (2021).

Zeptomole Detection of an Enzyme by a Simple Colorimetric Method
Kanako IHA,*1 Yuta KYOSEI,*1 Mayuri NAMBA,*1 Daiki MAKIOKA,*1 Sou YAMURA,*1 Satoshi WATABE,*2 Teruki YOSHIMURA,*3 and Etsuro ITO*1,*2,*4
*1 Department of Biology, Waseda University, 2-2 Wakamatsucho, Shinjuku, Tokyo 162-8480, Japan
*2 Waseda Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
*3 School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Tobetsu, Ishikari, Hokkaido 061-0293, Japan
*4 Graduate Institute of Medicine, Kaohsiung Medical University, No. 100 Shih-Chuan 1st Rd., Sanmin, Kaohsiung 80708, Taiwan
An enzyme immunoassay, in which an enzyme (e.g., alkaline phosphatase, ALP) is conjugated with an antibody, is a precise and simple protein detection method. Precise measurements of enzymes at low concentrations allow for ultrasensitive protein detection. The application of a phosphorylated substrate to ALP, followed by using a dephosphorylated substrate in thionicotinamide-adenine dinucleotide cycling, provides a simple and precise quantification of ALP. We describe a protocol for detecting ALP at the zeptomole level using a simple colorimetric method.