The reaction between 5,7-dihydroxytryptamine (5,7-DHT) and mushroom tyrosinase was studied by matrix-assisted laser desorption/ionization mass spectrometry of various samples drawn after different reaction times (0, 30, 60, 120, 240 and 360 min), ultrafiltered and immediately lyophilized. In order to evaluate the role of non-enzymatic oxidation, a portion of the ultrafiltered sample was left to react under an oxygen stream for a further 24 hr, lyophilized and analysed by the same method. Results show that, in the case of 5,7-DHT, oligomerization products are obtained which are structurally different from those produced by the same enzymatic reaction on 5,6-DHT. This is explained by the tendency of 5,7-DHT towards oxidation, since the oligomerization products originate from oxidized forms of 5,7-DHT
A Study of the Enzymatic Oligomerization of 5,7-Dihydroxytryptamine using Matrix-assisted Laser Desorption/Ionization Mass Spectrometry
BERTAZZO, ANTONELLA;ALLEGRI, GRAZIELLA;FAVRETTO, DONATA;
1996
Abstract
The reaction between 5,7-dihydroxytryptamine (5,7-DHT) and mushroom tyrosinase was studied by matrix-assisted laser desorption/ionization mass spectrometry of various samples drawn after different reaction times (0, 30, 60, 120, 240 and 360 min), ultrafiltered and immediately lyophilized. In order to evaluate the role of non-enzymatic oxidation, a portion of the ultrafiltered sample was left to react under an oxygen stream for a further 24 hr, lyophilized and analysed by the same method. Results show that, in the case of 5,7-DHT, oligomerization products are obtained which are structurally different from those produced by the same enzymatic reaction on 5,6-DHT. This is explained by the tendency of 5,7-DHT towards oxidation, since the oligomerization products originate from oxidized forms of 5,7-DHT
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