Department of Basic Teaching, Shanxi Agricultural University, Jinzhong, Shanxi 030801, China.
Rehabilitation Department, Shanxi Bethune Hospital, Taiyuan, Shanxi 030032, China.
Enzyme Microb Technol. 2023 Mar;164:110192. doi: 10.1016/j.enzmictec.2022.110192. Epub 2023 Jan 2.
Papain, as a classical cysteine protease, has been widely used in the food, pharmaceutical, chemical, and cosmetic fields. However, there are few information about the peroxidase-like activity of papain catalyzed substrate to produce fluorescence. In this study, we found that papain can catalyze HO to convert o-phenylenediamine (OPD), and generate fluorescence emission at 550 nm under 430 nm excitation. Based on this foundation, we report a papain/OPD/HO system for fluorescence detection of uric acid. The method exhibits a wide linear range of 10-1000 μM with a limit-of-detection of 4.6 μM, and has been successfully used to detect uric acid in human serum. This study paves the way for the application of papain as catalyst for fluorescence detection of different target biomolecules, such as cholesterol, glucose, lactate, for which HO is a product of oxidoreductase enzymes.
木瓜蛋白酶作为一种经典的半胱氨酸蛋白酶，已广泛应用于食品、医药、化工和化妆品等领域。然而，关于木瓜蛋白酶催化底物产生荧光的过氧化物酶样活性的信息却很少。在本研究中，我们发现木瓜蛋白酶可以催化 HO 将邻苯二胺（OPD）转化，在 430nm 激发下产生 550nm 的荧光发射。在此基础上，我们报告了一种基于木瓜蛋白酶/OPD/HO 体系的用于尿酸荧光检测的方法。该方法在 10-1000μM 的宽线性范围内表现出良好的线性关系，检测限低至 4.6μM，并已成功用于人血清中尿酸的检测。本研究为将木瓜蛋白酶作为过氧化物酶催化不同目标生物分子（如胆固醇、葡萄糖、乳酸等）的荧光检测奠定了基础，因为 HO 是氧化还原酶的产物。
