PURIFICATION AND CHARACTERIZATION OF DIAMINE OXIDASE FROM ARACHIS-HYPOGEA SEEDLINGS

Germination oi Arachis hypogea seeds is accompanied by a rapid increase in diamine oxidase (DAO) activity in the root and hypocotyl. However, much less activity in the cotyledon was observed during the growth of the seedlings. The enzyme was purified from peanut cotyledonless specimens to apparent homogeneity using ammonium sulphate precipitation and chromatography on DEAE cellulose, hydroxylapatite and Sephacryl s-200 columns. The molecular weight (M(r)) of the enzyme estimated by Sephadex G-200 gel filtration was 128,000 and the SDS gel electrophoresis gave a single band at the M(r) of 70,000. The enzyme readily oxidized putrescine, while cadaverine, agmatine and spermidine were oxidized more slowly. Optimum pH and K-m values for putrescine were 7.0 and 0.1 mM, respectively. Carbonyl reagents and copper-binding agents were effective inhibitors of peanut DAO.