Dudkowiak A, Nakamura C, Arai T, Miyake J
National Institute for Advanced Interdisciplinary Research, AIST/MITI, Ibaraki, Japan.
J Photochem Photobiol B. 1998 Aug 21;45(1):43-50. doi: 10.1016/S1011-1344(98)00158-4.
The interactions between chlorophyll a and synthesized peptides have been studied using optical spectroscopy. Three 30-residue peptides are designed and synthesized: an amphiphilic peptide without histidine (L), an amphiphilic peptide with histidine (L/H) and a hydrophilic peptide (K/E). These peptide properties thereby allow us to examine the effect of the peptide hydrophobicity and/or histidine residue on pigment-peptide interactions. On mixing with peptides, chlorophyll a has a main absorption band in the Qy region with the maximum at 672 nm. For all three peptides, fluorescence patterns show that at a low concentration of the peptide (0.05 mM) in aqueous solution, the energy is transferred among various forms of the pigment. Only peptide L/H at high concentration (0.5 mM) in solution retains the Qy band of chlorophyll a at 672 nm, and the emission is that typically seen for the monomeric form of the pigment. The aggregation of chlorophyll a is suppressed most strongly in the presence of the peptides L/H. The results suggest that chlorophyll a is ligated to a histidine residue, located in the hydrophobic region of the peptides L/H, and in surrounded or shielded by the peptide alpha-helixes.
利用光谱学研究了叶绿素a与合成肽之间的相互作用。设计并合成了三种30个残基的肽：一种不含组氨酸的两亲性肽（L）、一种含组氨酸的两亲性肽（L/H）和一种亲水性肽（K/E）。这些肽的特性使我们能够研究肽的疏水性和/或组氨酸残基对色素-肽相互作用的影响。与肽混合时，叶绿素a在Qy区域有一个主要吸收带，最大吸收波长为672nm。对于所有三种肽，荧光模式表明，在水溶液中低浓度肽（0.05mM）时，能量在色素的各种形式之间转移。只有溶液中高浓度（0.5mM）的肽L/H保留了叶绿素a在672nm处的Qy带，且发射是色素单体形式通常出现的发射。在肽L/H存在下，叶绿素a的聚集受到最强烈的抑制。结果表明，叶绿素a与位于肽L/H疏水区域的组氨酸残基结合，并被肽的α-螺旋包围或屏蔽。
