A NOVEL ENZYME ENANTIO-SELECTIVELY SYNTHESIZES (R)SALSOLINOL, A PRECURSOR OF A DOPAMINERGIC NEUROTOXIN, N-METHYL(R)SALSOLINOL

In the human brain, only (R)enantiomer of ethyl-6,7-dihydroxy-1,2,3,4- tetrahydroisoquinoline ((R)salsolinol) and N-methylsalsolinol, a dopam inergic neurotoxin, were detected, suggesting their enzymatic biosynth esis. This paper reports the isolation and characterization of a novel enzyme, which enantio-selectively synthesizes (R)salsolinol from dopa mine and acetaldehyde. Dopamine, acetaldehyde, formaldehyde and pyruvi c acid were the substrates of this synthase, whereas N-methyldopamine, adrenaline, noradrenaline and L-DOPA were not. The possible function of this enzyme under physiological and pathological conditions in the brain is discussed.