Kinetics of the Interaction between Pig‐Plasma Benzylamine Oxidase and Various Monoamines

The kinetics of interaction between pig‐plasma benzylamine oxidase and a series of amine substrates have been investigated by conventional initial‐velocity studies, and by determination of transient rates of aldehyde formation and reduction of the enzymatic 470‐nm chromophore using stopped‐flow techniques. Kinetic parameters for the various processes and different substrates are reported. The results obtained provide evidence that reduction of the enzyme by different monoamines leads to the formation of a common reduced enzymatic intermediate, reoxidation of which appears to be rate‐limiting in all the reactions examined. Km‐values for the different substrates are inversely proportional to second‐order rate constants for the corresponding reduction process, and exhibit a striking correlation to the base strength of the respective amines. The latter observation may suggest that benzylamine oxidase acts exclusively on the non‐protonated form of amine substrates.