Stereochemistry of copper amine oxidase reactions

The stereochemical course of the oxidation of stereospecifically deuterated dopamine and tyramine, catalyzed by porcine plasma amine oxidase, has been investigated using 1H NMR spectroscopy. The oxidation proceeds with loss of the pro-R hydrogen at C-1. This stereochemistry is in contrast to that observed with the analogous copper containing oxidases isolated from pea seedlings (pro-S) and bovine plasma (nonstereospecific). There is no precedent for these three distinct stereochemical reaction courses to be followed by enzymes in the same class. Mechanistic differences among the three enzymes are evident from the profiles of solvent exchange into reaction products; however, these differences cannot account for the overall differential stereochemical courses observed.