Variation in monoamine oxidase activity in rat brain crude mitochondrial fractions prepared by rate zonal centrifugation.

Rat brain crude mitochondrial fractionated by rate zonal centrifugation using an iso-osmotic gradient of Ficoll and sucrose. The results demonstrated that the isolated fractions were biochemically heterogeneous with regard to the enzymes, monoamine oxidase (MAO), NADH dehydrogenase and succinate dehydrogenase. When the activity of MAO was plotted as % of the highest specific activity towards tyramine, kynuramine oxidation remained fairly constant in fractions 10 to 30 but tyramine and dopamine showed separate peaks of activity in fractions 21 and 32 respectively. Sonic oscillations of separated particulate fractions did not change the ratios of various monoamine deamination when compared to the intact particles.