Abstract
A method for assaying diamine oxidase (DAO) by high performance liquid chromatography (HPLC) is described. The method is based on a pre-column reaction: DAO oxidizes putrescine or cadaverine of peroxidase, hydrogen peroxide oxidizes serotonin (5-hydroxytryptamine; 5-HT) to an oxidized compound. 5-HT is analyzed by HPLC, and DAO activity is measured from decreased 5-HT values. The assay is quantitative and reproducible with a detectable range up to 70 mU/ml. The intra-assay coefficient of variation (C.V.) was 5.5% with a recovery of 97.0% at the DAO activities of 11.4, 28.9, and 45.6 mU/ml. A close correlation was found between the results of the present method and the 2, 2'-azino-di (3-ethylbenzthiazoline-6-sulfonic acid) method.
