54] Amine oxidases: A. Amine oxidase from steer plasma [formula omitted

Abstract

Publisher Summary This chapter discusses about the amine oxidases and describes the procedure for the determination of amine oxidase from steer plasma and diamine oxidase (histaminase) from hog kidney. In the case of the determination of amine oxidase from steer plasma, the oxidative deamination of amines is usually followed by the measurement of oxygen consumption or ammonia production. The spectrophotometric assay used involves the measurement of the benzaldehyde produced during the oxidative deamination of benzylamine and depends on the difference in the absorption spectrum of benzaldehyde and benzylamine at 250 mμ. The molar extinction coefficient of benzaldehyde is 13,000, whereas that of benzylamine is <200. In the case of the determination of diamine oxidase (histaminase) from hog kidney, diamine oxidase catalyzes the oxidation of histamine and various diamines with the consumption of 1 mole of oxygen and the production of 1 mole of aldehyde, 1 mole of NH3, and 1 mole of H2O2. In the presence of catalase the H2O2 is converted to H2O and 0.5 mole of O2. Assay of diamine oxidase, therefore, has depended on disappearance of histamine, consumption of oxygen, production of ammonia, or the coupled oxidation of indigodisulfonate. The chapter describes the assay based on the oxygen consumption obtained with histamine as the substrate in the presence of added catalase.