Melanogenesis by tyrosinase action on 3,4-dihydroxyphenylalanine (DOPA) in the presence of polyethylene glycol: a matrix-assisted laser desorption/ionization mass spectrometric investigation

被引:3
作者
Bertazzo, A
Vogliardi, S
Favretto, D
Costa, CVL
Allegri, G
Traldi, P
机构
[1] CNR, Area Ric, CSSRCC, Corso Stati Uniti 4, I-35100 Padua, Italy
[2] Univ Padua, Dipartimento Sci Farmaceut, I-35100 Padua, Italy
[3] CNR, CSCTCMET, I-35100 Padua, Italy
关键词
D O I
10.1002/rcm.339
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
The enzymatic reaction between DOPA and tyrosinase, the enzyme considered to be responsible for melanogenesis, was carried out in the presence of polyethylene glycol (PEG). This choice was made in order to increase the solubility of melanins, since these polymers are highly insoluble. The reaction mixtures were sampled at different times, immediately ultrafiltered to remove the enzyme, lyophilized, and analyzed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The results were very different from those obtained in the absence of PEG. Only a few oligomers of dihydroxyindole (DHI) and dihydroxyindole-2-carboxylic acid (DHICA) were detected in low abundances, whereas new species originating from reaction of PEG with species belonging to the Raper-Mason pattern appeared. The results show that, in the presence of PEG, tyrosinase-catalyzed oligomerization of DOPA exhibits kinetics slower than those observed in the absence of the polymer. However, melanogenesis still takes place in the presence of PEG, as indicated by the formation of black pigments and by the detection of DHI and DHICA oligomers, considered to be the first intermediates in melanin formation. Copyright (C) 2001 John Wiley & Sons, Ltd.
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页码:1061 / 1067
页数:7
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