A Simple and Rapid Method for Screening of Nocardioides simplex Mutant with High Cholesterol Oxidase Activity

摘要

CHO (EC 1.1.3.6) is a widely used enzyme that has industrial and clinical uses related to hypertension and obesity. This enzyme is used for the clinical determination of total or free serum cholesterol by coupling with the related enzymes [Allain et al., 1974]. CHO catalyzes the first step of the cholesterol degradation, oxidizing the cholesterol to 4-cholestene-3-one through the reduction of the flavin adenine dinucleotide cofactor [Uwajima et al., 1974]. The reduced cofactor is recycled to the oxidized form by the reduction of oxygen to hydrogen peroxide (Fig. 1A). The hydrogen peroxide is then coupled to the horseradish peroxidase as a substrate, and oxidizes a color reagent into a colored product [Murooka and Yamashita, 2001; Xiang and Sampson,2004]. This colored product has been used as the basis for the measurement of CHO activity.