Charge equilibria and pKa of malvidin-3-glucoside by electrophoresis

被引:48
作者
Asenstorfer, RE [1 ]
Iland, PG [1 ]
Tate, ME [1 ]
Jones, GP [1 ]
机构
[1] Univ Adelaide, Sch Agr & Wine, Glen Osmond, SA 5064, Australia
基金
澳大利亚研究理事会;
关键词
anthocyanins; electrophoresis; ionization potentials; pK(a); red wine color;
D O I
10.1016/S0003-2697(03)00249-5
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
Paper electrophoresis has been used over the pH range 1.2 to 10.4 to measure apparent pK(a) values for malvidin-3-O-glucoside of pKa(1) 1.76 +/- 0.07, pK(a2) 5.36 +/- 0.04, and pK(a3) 8.39 +/- 0.07. Using solvent partitioning between buffered aqueous solutions and n-octanol, several micro-pK(a) constants for malvidin-3-O-glucoside were also identified, highlighting the complex nature of malvidin-3-glucoside equilibria. As a nonspectrophotometric procedure, the charge-dependent electrophoretic mobility method provided independent information on the net charge and color of anthocyanin species at wine pH (ca. 3.6). At this pH, the color of malvidin-3-glucoside in red wines is consistent only with the uncharged quinonoidal base as a major colored component of the equilibria. (C) 2003 Elsevier Science (USA). All rights reserved.
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页码:291 / 299
页数:9
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