The distribution of catechol- O-methyltransferase in pig liver and brain

Subcellular fractionation studies of pig liver and brain show the enzyme catechol- O-methyl-transterase (E.C. 2.1.1.6) to be confined to the soluble phase with no appreciable amounts being associated with paniculate material. The regional distribution of the enzyme in brain is relatively even. Impure preparations of the enzyme exist in a high molecular weight form and a reversibly inhibitory material may be separated from purified preparations of the enzyme by high-speed centrifugation. The presence of this material results in a non-linear dependence of initial velocity of the reaction catalysed on protein concentration.