Semicarbazide-sensitive amine oxidase inhibitory activity of galacturonic acid hydroxamate

In the literature, semicarbazide-sensitive amine oxidase (SSAO) in plasma was elevated in diabetes mellitus and heart failure. SSAO catalyzed the oxidative deamination of various amines to produce hydrogen peroxide, which is one possible source of oxidative stresses. In this research, galacturonic acid hydroxamate (galA-nHOH), but not galA, effectively inhibited SSAO activities from bovine plasma and porcine plasma in a dose-dependent manner, and the IC₅₀ values were 0.041 and 0.018 mM, respectively. The SSAO activities from bovine plasma and pig plasma were confrmed by the SSAO specifc inhibitor of semi-carbazide. using AO activity staining in the 7.5% native-PAgE gels, it was also revealed that galA-nHOH had inhibitory activities against SSAO from bovine plasma. galA-nHOH showed mixed noncompetitive inhibition against bovine SSAO in respect to benzylamine (substrate) and benzylamine-SSAO (substrate-enzyme complex). It was found that the V'_max and K'_m values were reduced in the presence of galA-nHOH (0.03 mM).