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Molecular properties of polyamine oxidase from cowpea primary leaves

He Shenggen, Huang Xuelin, Fu Jiarui

The School of Life Sciences,Zhongshan University.Guangzhou 510275,Guangdong

Abstract

The enpolyamine oxidase is a dimer of identical subunits. The enzyme contained two Cu~(2+) ions per molecule in its native state, and its isoelectric point was about 6.2 determined by isoelectric focusing with the Rotofor System (Bio-Rad). The absorption spectrum of the enzyme showed a well-defined peak at 278 nm and a small peak at 500 nm. The chemical modification studies with p-chloromercuribenzoate, 2, 2^-dinitro-5, 5^-dithiodibenzoic acid, N-acetylimidazole, p-nitrobenzenesulfonyl fluoride, trinitrobenzenesulfonic acid, N-bromosuccinimide, iodoacetamide and diethylpyrocarbonate (DEPC) showed that histidine residues were involved in the active sites and thiol groups, tyrosyl residues, lysyl residues and tryptophyl residues were non-essential to the catalytic activity of the enzyme. The kinetic parameters of the enzyme partially inactivated by DEPC, imply that histidine residues might be the catalytic site of the enzyme.

Key words: Cowpea;Polyamine oxidase;Chemical modification;Active center

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Citing This Article：

He Shenggen, Huang Xuelin, Fu Jiarui. Molecular properties of polyamine oxidase from cowpea primary leaves. Acta Physiol Sin 2001; 53 (5): (in Chinese with English abstract).