The kinetics of phenethylhydrazine oxidation by monoamine oxidase.

1. In the presence of the substrate benzylamine, phenethylhydrazine has been shown to be a competitive inhibitor of monoamine oxidase from rat liver and pig brain. 2. Phenethylhydrazine is also a substrate for monoamine oxidase. Reciprocal plots for hydrazine oxidation give families of intersecting lines in contrast with the parallel lines previously reported for tyramine oxidation. 3. Two possible modifications of the mechanism obeyed by tyramine oxidation are suggested, but the product inhibition results are insufficient to distinguish between these two mechanisms.