摘要
采用紫外 可见光谱法研究了在pH 6 5的缓冲溶液中Cu(Ⅱ )离子对多巴色素的催化作用。在通氮除氧的体系中 ,Cu(Ⅱ )离子显著加快多巴色素 (DC)于 4 75nm波长的褪色速度 ,并同时出现在 30 0～ 80 0nm波长范围内的全程吸收。实验结果表明 :Cu(Ⅱ )离子催化重排多巴色素生成的主要产物为 5 ,6 二羟基吲哚 2 羧酸 (DHICA) ,其反应前期对于DC为动力学一级反应 ;而且Cu(Ⅱ )离子可进一步催化 5 ,6 二羟基吲哚(DHI)和DHICA形成吲哚醌 (即吲哚 5 ,6 醌和吲哚 5 ,6 醌 2 羧酸 )的反应 ,吲哚醌一经生成 ,立即聚合形成黑色素。
The effect of Cu(Ⅱ) ions on dopachrome has been studied by means of UV-Vis spectra in buffer solution at pH 6.5. Cu(Ⅱ) ions markedly accelerated the rate of bleaching of dopachrome (DC) at 475 nm and simultaneously exhibited general absorption in the range of 300-800 nm in the system with oxygen removed by bubble nitrogen gas. The experimental results revealed that Cu(Ⅱ) ions catalyzed not only the rearrangement of DC to yield mainly 5,6-dihydroxyindole-2-carboxylic acid (DHICA) on first-order kinetics with respect to DC in the first part of the reaction, but also the reaction of 5,6-dihydroxyindole (DHI) and DHICA to form indole-5,6-quinone (IQ) and indole-5,6-quinone-2-carboxylic acid (IQCA), which would immediately polymerize to yield melanin.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2004年第7期834-836,共3页
Spectroscopy and Spectral Analysis
基金
江苏省教育厅自然科学基金
苏州大学青年基金资助项目
