Mathies R A, Brito Cruz C H, Pollard W T, Shank C V
Department of Chemistry, University of California, Berkeley 94720.
Science. 1988 May 6;240(4853):777-9. doi: 10.1126/science.3363359.
Femtosecond optical measurement techniques have been used to study the primary photoprocesses in the light-driven transmembrane proton pump bacteriorhodopsin. Light-adapted bacteriorhodopsin was excited with a 60-femtosecond pump pulse at 618 nanometers, and the transient absorption spectra from 560 to 710 nanometers were recorded from -50 to 1000 femtoseconds by means of 6-femtosecond probe pulses. By 60 femtoseconds, a broad transient hole appeared in the absorption spectrum whose amplitude remained constant for about 200 femtoseconds. Stimulated emission in the 660- to 710-nanometer region and excited-state absorption in the 560- to 580-nanometer region appeared promptly and then shifted and decayed from 0 to approximately 150 femtoseconds. These spectral features provide a direct observation of the 13-trans to 13-cis torsional isomerization of the retinal chromophore on the excited-state potential surface. Absorption due to the primary ground-state photoproduct J appears with a time constant of approximately 500 femtoseconds.
飞秒光学测量技术已被用于研究光驱动跨膜质子泵细菌视紫红质中的初级光过程。用一个60飞秒的泵浦脉冲在618纳米波长下激发光适应态的细菌视紫红质，并通过6飞秒的探测脉冲记录从-50到1000飞秒的560至710纳米的瞬态吸收光谱。到60飞秒时，吸收光谱中出现一个宽的瞬态空穴，其幅度在约200飞秒内保持恒定。660至710纳米区域的受激发射和560至580纳米区域的激发态吸收迅速出现，然后在0至约150飞秒内发生位移并衰减。这些光谱特征直接观察到了激发态势能面上视黄醛发色团从13-反式到13-顺式的扭转异构化。初级基态光产物J引起的吸收以约500飞秒的时间常数出现。
