Bovine serum amine oxidase: some differences between chromatographically defined forms including sensitivity to inhibition by dithiomolybdate.

1. Bovine serum amine oxidase (BSAO) forms, defined by DEAE-cellulose and hydroxyapatite chromatography, were shown to have different kinetic characteristics with p-dimethylaminobenzylamine as a substrate; there was also some variation in heat sensitivity. 2. The forms showed similar sensitivity to inhibition by aminoguanidine but there were differences with respect to dithiomolybdate. 3. The results also provided some support for the view that both subunits were active catalytically. 4. It is concluded that while the forms were interconvertible, the practice of pooling different chromatographic fractions may not be acceptable in all circumstances. 5. While inhibition by dithiomolybdate is of biochemical interest it is concluded that inhibition of BSAO by thiomolybdates is unlikely to play a role in the clinical syndromes which are common in cattle exposed to Mo in the herbage.