Purification and characterization of diamine oxidase from rice embryos

Diamine oxidase of rice seedlings has been purified 1800-fold to homogeneity. The MW of the enzyme as determined by Sephadex G-100 gel filtration was 12.3 × 10⁴ and the enzyme contained two identical subunits each with a MW of 6.12 × 10⁴. The optimal temperature and pH for the enzyme were 30° and 7.5 respectively and the enzyme followed typical Michaelis kinetics with a K_m of 10^?5 M. Each enzyme molecule contained four molecules of FAD.