Photoinduced Reduction of Methylviologen by Ascorbate Using Chlorophyllin in Liposome System
作者:Seiji Hidaka、Eizo Matsumoto、Fujio Toda
DOI:10.1246/bcsj.58.207
日期:1985.1
Photoindeced electron transport across bilayer lipid membrane was studied, using chlorophyllin (Chln), a water-soluble derivative of chlorophyll. Photoreduction of methylviologen (MV2+) by ascorbate was observed only in the liposome system containing ascorbate in the internal aqueous phase and MV2+ in the external aqueous phase. This suggests asymmetry of bilayer lipid membrane. This reaction rate was not affected by the addition of carbonyl cyanide m-chlorophenylhydrazone in the system buffered by tris(hydroxymethyl)aminomethane (Tris), but strongly affected by N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid. In the system buffered by Tris, a proton carrier is not Chin having carboxyl groups but Tris possessing primary amine group. Replacement of the central Mg of Chin with Zn gives a higher rate of MV2+ photoreduction, but when Cu was used in place of Zn, photoreduction was not observed. The central metal may affect the redox potential and the life time of excited Chln.
利用叶绿素(Chln)这种叶绿素的水溶性衍生物,研究了双层脂膜上的光诱导电子传递。只有在内部水相中含有抗坏血酸,外部水相中含有 MV2+ 的脂质体系统中,才能观察到抗坏血酸对甲基维罗庚(MV2+)的光还原作用。这表明双层脂膜不对称。在由三羟甲基氨基甲烷(Tris)缓冲的体系中,加入间氯苯基腙羰基反应速率不受影响,但加入 N-2-羟乙基哌嗪-N′-2-乙磺酸则影响很大。在由 Tris 缓冲的体系中,质子载体不是具有羧基的 Chin,而是具有伯胺基团的 Tris。用锌代替钦的中心镁可提高 MV2+ 的光反应速率,但用铜代替锌时,则观察不到光反应。中心金属可能会影响氧化还原电位和激发 Chln 的寿命。