山杏种皮黑色素与Cu^2＋和Zn^2＋络合性质的研究

Investigation of Cu^(2+) and Zn^(2+) binding in melanin from teatae of Prunus armeniaca var.ansu

【目的】研究山杏种皮黑色素与Cu2+和Zn2+络合的相关性质,为山杏种皮黑色素以及其他植物黑色素的开发利用提供依据。【方法】采用电位滴定、紫外-可见光差示吸收光谱和红外光谱对山杏种皮黑色素与Cu2+和Zn2+的络合物进行分析。【结果】Cu2+和Zn2+与山杏种皮黑色素络合后,均能促进山杏种皮黑色素酸性位点的去质子化作用,但Cu2+的促进作用更强,结合更为牢固;随pH值升高,山杏种皮黑色素中解离出的络合位点增多,络合Cu2+能力增强。【结论】Cu2+和Zn2+主要与山杏种皮黑色素中羰基发生络合作用,氨基和羟基参与了络合。

【Objective】 The coordination chemistry of Cu2＋ and Zn2＋ in the melanin from testae of Prunus armeniaca var.ansu was investigated to lay a foundation for utilization of the melanin and other phytomelanins.【Method】 Potentiometric titration,ultraviolet-visible （UV-Vis） differential and Fourier transform infrared（FT-IR） spectroscopy were employed.【Result】 The complexation of the metal ions promote deprotonation of the acidic melanin sites and Cu2＋ complexation more obviously and more tightly than that of Zn2＋.The melanin had more binding capacity with Cu2＋ at high pH value than at neutral condition.【Conclusion】 The essential interactions of the metal ions（Cu2＋ or Zn2＋） went on with carboxyl groups and amine and hydroxyl were also involved in complexation formation.