Effect of NAD(P)H:quinone oxidoreductase on tyrosinase-mediated oxidation of opioid neuropeptides Leu-enkephalin and Met-enkephalin.
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.
Rescigno
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Istituto di Chimica Biologica, Università di Cagliari, Italy.
Porcu
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MC
Olianas
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Rinaldi
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AC
Sanjust
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Cocco
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D
Rinaldi
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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*
D009243:NAD; D009249:NADP; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D014442:Monophenol Monooxygenase; C087049:NADPH - phenanthrenequinone oxidoreductase; D011808:Quinone Reductases