Wachtveitl J, Spörlein S, Satzger H, Fonrobert B, Renner C, Behrendt R, Oesterhelt D, Moroder L, Zinth W
Institut für Physikalische und Theoretische Chemie, Goethe-Universität Frankfurt, 60439 Frankfurt, Germany.
Biophys J. 2004 Apr;86(4):2350-62. doi: 10.1016/S0006-3495(04)74292-7.
Structural changes of peptides containing the azobenzene dye 4-aminomethyl-phenylazobenzoic acid (AMPB) are studied with ultrafast spectroscopy. AMPB peptides are a new class of molecules where the photoisomerizable dye azobenzene is linked to the peptide moiety via a flexible methylene spacer. The ultrafast reactions in the femtosecond to nanosecond time domain are investigated for the optical switch AMPB, a linear and cyclic octapeptide, and a bicyclic octapeptide containing an additional disulfide bridge. These molecules with increasing conformational constraints are studied for the cis to trans and the trans to cis photoreactions. For the cis to trans reaction the isomerization of the chromophore occurs fast in the 1-ps range, whereas it is slower (10-ps range) in the trans to cis reaction. In all peptides the structural changes of the chromophore lead to modifications in the peptide structure in the 10-ps-1-ns time range. The results indicate that the chromophore AMPB acts simultaneously as a fast molecular switch and as a sensor for initial conformational dynamics in the peptide. Experiments in the mid-infrared range where the structural changes of the peptide backbone are directly observed demonstrate that the essential part of the structural dynamics in the bicyclic AMPB peptide occurs faster than 10 ns.
利用超快光谱研究了含有偶氮苯染料4-氨甲基-苯基偶氮苯甲酸（AMPB）的肽的结构变化。AMPB肽是一类新型分子，其中可光异构化的染料偶氮苯通过柔性亚甲基间隔基与肽部分相连。研究了光学开关AMPB、线性和环状八肽以及含有额外二硫键的双环八肽在飞秒到纳秒时间域内的超快反应。对这些构象限制逐渐增加的分子进行了顺式到反式以及反式到顺式光反应的研究。对于顺式到反式反应，发色团的异构化在1皮秒范围内快速发生，而在反式到顺式反应中则较慢（10皮秒范围）。在所有肽中，发色团的结构变化在10皮秒到1纳秒的时间范围内导致肽结构的改变。结果表明，发色团AMPB同时作为快速分子开关和肽中初始构象动力学的传感器。在中红外范围内直接观察肽主链结构变化的实验表明，双环AMPB肽中结构动力学的主要部分发生在10纳秒以内。
