Role of a non-ionic detergent upon maintenance and radioisotopic determination of enzymes catechol-O-methyltransferase and monoamine oxidase in brain and adrenal tissues.

1. The effect of different concentrations of Triton-X-100, used as homogenization media for enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), was investigated. 2. Brain and adrenal COMT showed significant activation when treated with 0.2% Triton-X-100. 3. The activity of MAO in the brain and adrenal tissue was markedly inhibited by Triton-X-100 and the concentration required to provoke the inhibition was found to be much lower than that required to activate COMT. 4. When the tissues were kept in KCl-Triton-X-100 (0.9%-0.2%) for longer periods to study time related responses, brain COMT showed progressive increases in activity up to 4 hours of treatment and the increase persisted till 24 hours. Similar treatment of MAO enzyme preparation with Triton-X-100 induced strong inhibition of the enzyme activity (60% at 5 minutes and 55% at 24 hours). 5. The results suggest that the use of Triton-X-100 should be considered with extra care for determination of catecholamine regulating enzymes. It can activate one enzyme system whereas inhibit the other one. Therefore, different homogenization medias are required for the assay of enzymes of metabolism (MAO and COMT) and synthesis (tyrosine hydroxylase, phenylethano-l-amine-N-methyltransferase and dopamine beta hydroxylase).