Kinetic studies of the interaction between spergualin or 15-deoxyspergualin and amine oxidase from bovine plasma.

Spergualin (SG) and 15-deoxyspergualin (DSG) are derivatives of spermidine. Their substrate and inhibitor activities toward amine oxidase from bovine plasma were determined. SG was a good substrate of amine oxidase next to spermidine. The Km and Vmax for SG were 46.5 microM and 0.429 microM/minute, respectively, whereas the Km and Vmax for spermidine were 111 microM and 3.75 microM/minute, respectively. Thus SG has about two-fold stronger affinity to amine oxidase than spermidine, but its catalysis rate was one ninth of spermidine. In contrast, DSG was hardly oxidized and inhibited spermidine oxidation at low concentration. Affinity of both compounds for amine oxidase was determined by inhibition kinetics using benzylamine as substrate. SG and DSG competitively inhibited amine oxidase activity showing the Ki values of 175 microM and 7.46 microM, respectively.