Mechanistic studies of mouse polyamine oxidase with N1,N12-bisethylspermine as a substrate.

ABSTRACT: In mammalian cells, the flavoprotein polyamine oxidase catalyzes a key step in the catabolism of polyamines, the oxidation of N1-acetylspermine and N1-acetylspermidine to spermidine and putrescine, respectively. The mechanism of the mouse enzyme has been studied with N1,N12-bisethylspermine (BESPM) as a substrate. At pH 10, the pH optimum, the limiting rate of reduction of the flavin in the absence of oxygen is comparable to the k(cat) value for turnover, establishing reduction as rate-limiting. Oxidation of the reduced enzyme is a simple second-order reaction. No intermediates are seen in the reductive or oxidative half-reactions. The k(cat) value decreases below a pK(a) of 9.0. The k(cat)/K(m) value for BESPM exhibits a bell-shaped pH profile, with pK(a) values of 9.8 and 10.8. These pK(

SUBMITTER: Royo M 

PROVIDER: S-EPMC1635011 | biostudies-literature | 2005 May

REPOSITORIES: biostudies-literature