A NOVEL TYPE MITOCHONDRIAL MONOAMINE-OXIDASE FROM THE LIVER OF SKIPJACK TUNA (KATSUWONUS-PELAMIS) - PURIFICATION AND CHARACTERIZATION

A novel type of monoamine oxidase (EC. 1.4.3.4) present in the liver o f skipjack tuna (Katsuwonus pelamis) was extracted from mitochondrial preparations by Triton X-100. The enzyme was purified by ammonium sulp hate fractionation, followed by Sephadex G-200, butyl-toyopearl 650 M, phenyl-toyopearl 650 M and hydroxyapatite chromatography. The molecul ar weight of the enzyme was estimated to be about 110 000 by gel filtr ation on Sephadex G-200. The enzyme was activated by Mn2+, but was inh ibited by Cu2+, Zn2+ and p-chloromercuribenzoic acid (PCMB). Furthermo re, the enzyme was completely inhibited by Hg2+ and 5,5'-dithiobis(2-n itrobenzoic acid) (DTNB).