Reduction of dihydroxyphenylacetic acid by a novel enzyme in the rat brain.
A novel enzyme that converts dihydroxyphenylacetic acid (DOPAC) to dihydroxyphenylethanol (DOPET) was found to be present in the microdialysate of the rat brain. The enzyme, named DOPAC reductase, was inhibited by EDTA and stimulated by divalent cations like Zn2+, Mn2+, Co2+ and Cu2+. Its Km, pH optimum and temperature optimum were found to be 32 +/- 2 microM, 7.5 and 40 degrees, respectively. The equivalent acid metabolite of noradrenaline, 3,4-dihydroxymandelic acid, and the methoxylated acids of both noradrenaline and dopamine, 3-methoxy-4-hydroxymandelic acid and 3-methoxy-4-hydroxyphenylacetic acid, were found not to be substrates of DOPAC reductase. Thus, DOPAC reductase may be an enzyme that is specifically involved in the one-step conversion of DOPAC to DOPET in the central metabolism of dopamine.
Xu
C L
CL
Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore.
Sim
M K
MK
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000378:metabolism; D051381:Rats
D004791:Enzyme Inhibitors; D015102:3,4-Dihydroxyphenylacetic Acid; C005975:3,4-dihydroxyphenylethanol; D004492:Edetic Acid; D010088:Oxidoreductases; C097068:dihydroxyphenylacetic acid reductase; D010626:Phenylethyl Alcohol