STUDIES ON CATECHOLAMINE-SYNTHESIZING ENZYMES

The purification and characterization of three enzymes involved in the biosynthesis of catecholamines is reviewed. Polyclonal antibodies against native tyrosine hydroxylase (TH) were raised in rabbits, and these antibodies inhibit TH activity. Polyclonal antibodies were also raised in rabbits against a segment of TH (TH-16) and these antibodies stimulate enzymatic activity. In addition, mouse monoclonal antibodies were raised but exerted no significant effect on enzymatic activity. The three types of antibodies were used for immunohistochemical localization of dopamine neurons in the CNS. Studies on activation of TH revealed that phosphorylation of the enzyme by protein kinases plays an important role in the short-term regulation of the enzyme activity. Dopamine β-hydroxylase (DBH) was purified from human and rat pheochromocytoma tumors, and polyclonal antibodies against human and rat DBH were raised in rabbits. Enzyme inhibition studies with the corresponding antibodies revealed poor interspecies crossreactivity. Phenylethanolamine N-methyl-transferase (PNMT) was purified from bovine and rat adrenal glands. Polyclonal antibodies raised against rat adrenal PNMT were used for immunohistochemical localization of PNMT-containing neurons. The presence of PNMT-containing cell bodies in two clusters, termed C1 and C2, were found; ascending and descending projections were demonstrated. © 1990.