Competitive inhibition of catechol O-methyltransferase by RO-4-4602.

RO-4-4602, a peripheral L-DOPA decarboxylase (EC 4.1.1.28) inhibitor was shown to also inhibit the activity of catechol O-methyltransferase (COMT) (EC 2.1.1.6). Kinetic study indicated that the inhibition is of a competitive nature. The apparent Ki values of 7 X 10(6), 5.3 X 10(-6, and 9 X 10-6) M calculated from Lineweaver-Burke plots when dopamine, norepinephrine, and epinephrine, respectively, were used as substrate, showed that this drug is the most potent inhibitor of COMT yet known.