A refined HPLC method to measure catecholamine-o-methyltransferase activity in selected brain regions.

An improved HPLC method, with fluorogenic detection, for the determination of catecholamine-o-methyltransferase (COMT) activity in the brain has been developed. A catechol compound, 3,4-dihydroxybenzoic acid (3,4DOBA), was used as a highly fluorogenic substrate for COMT. The meta- and para-methylated products formed enzymatically from the substrate, after incubation with a brain region homogenate, were separated and measured using HPLC with fluorescence detection. This described method resulted in a more definitive enzyme product quantification with shorter analysis time than that previously described in the literature. This approach was used successfully to study COMT activity in vitro from small discreet brain regions of individual rats.