title: Effect of NAD(P)H:quinone oxidoreductase on tyrosinase-mediated oxidation of opioid neuropeptides Leu-enkephalin and Met-enkephalin.
abstract: In vitro experiments are reported showing that NAD(P)H:(quinone acceptor) oxidoreductase (QR), purified from Glycine max seedlings, reduces Leu- and Met-enkephalin-tyrosinase oxidation products, in the presence of NADH or NADPH. QR was not capable to catalyze the reduction of N-acetyl-dopaquinone formed by the cation of mushroom tyrosinase on N-acetyl-L-tyrosine, while it was able to reduce dopachrome. The results support the hypothesis that QR can inhibit the formation of melanin-like compounds, as catalyzed by the action of tyrosinase on Leu-enkephalin and Met-enkephalin. It is proposed that, in the presence of NAD(P)H as the electron donor, the inhibition occurs by the specific conversion of the dopachrome-derivative into the reduced precursor, leucodopachrome-derivative.
authors.affiliation: Istituto di Chimica Biologica, Università di Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Rescigno
authors.forename: M C
authors.initials: MC
authors.lastname: Porcu
authors.forename: A
authors.initials: A
authors.lastname: Olianas
authors.forename: A C
authors.initials: AC
authors.lastname: Rinaldi
authors.forename: E
authors.initials: E
authors.lastname: Sanjust
authors.forename: D
authors.initials: D
authors.lastname: Cocco
authors.forename: A
authors.initials: A
authors.lastname: Rinaldi
mesh_terms: D004743:Enkephalin, Leucine / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000378:metabolism* / Q000494:pharmacology; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D011808:Quinone Reductases / Q000378:metabolism*; D013025:Glycine max / Q000201:enzymology*
chemical_list: D009243:NAD; D009249:NADP; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D014442:Monophenol Monooxygenase; C087049:NADPH - phenanthrenequinone oxidoreductase; D011808:Quinone Reductases