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Pig kidney diamine oxidase (DAO) and other semicarbazide-sensitive amine oxidases (SSAO) show clear substrate-inhibition kinetics and a reaction-scheme mechanism based on two substrate binding sites. We evaluated several reaction scheme mechanisms with a non-linear regression program (NCSS), estimating R 2 , the constants of the equations and their standard errors and we determined the deviation of experimental data from theoretical equations. The best fit was obtained with a "dead end" mechanism with two binding sites. Based on this scheme, other schemes for a two-substrate reaction and for mechanisms of inhibition were constructed. These reaction schemes, even at low substrate concentration, fitted experimental data better than Michaelis-Menten kinetics, and provided information on the mechanisms of action of inhibitors. The presence of two substrate-binding sites on pig kidney DAO was confirmed by all experimental data. [ABSTRACT FROM AUTHOR]

The copper-containing amine oxidases of the class EC 1.4.3.6 share many biochemical similarities. They contain cupric copper and catalyse the same general reaction. In mammals, diamine oxidase has a role in the metabolism of histamine, some other diamines and spermine oxidase, involved in the metabolism of polyamines. However, the functional role of benzylamine oxidase (BAO) and the tissue semicarbazide-sensitive amine oxidases (SSAO) is still under investigation. Circulating BAO is derived from the tissue SSAO. It has a high affinity for benzylamine and its role in the extra-cellular matrix includes the maturation of pro-elastin and control of the inflammatory process. [ABSTRACT FROM AUTHOR]