Dynamic infrared band-band spectroscopy of peripheral light-harvesting complexes from R-acidophila

被引:6
作者
Kumble, R
Howard, TD
Cogdell, RJ
Hochstrasser, RM [1 ]
机构
[1] Univ Penn, Dept Chem, Philadelphia, PA 19104 USA
[2] Univ Glasgow, Inst Biomed & Life Sci, Div Mol Biol & Biochem, Glasgow G12 8QQ, Lanark, Scotland
基金
英国生物技术与生命科学研究理事会; 美国国家科学基金会; 美国国家卫生研究院;
关键词
bacteriochlorophyll; Rhodopsuedomonas acidophila; band-band spectrum;
D O I
10.1016/S1010-6030(01)00505-6
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Infrared (IR) kinetic spectroscopy measurements have been employed to investigate and compare the electronic structure of B800 and B850 bacteriochlorophyll (BChl) pigment aggregates within peripheral (LH2) antenna complexes of photosynthetic purple bacteria. Following initial excitation of the B800 chromophores at 800 nm, a strong absorption band centred at similar to1.3 mum was observed in the transient spectrum which is characteristic of monomeric BChls. Evolution of a transient spectrum in the near-IR and IR regions was then tracked while the excitation energy migrated to the B850 chromophores on a similar to0.9 ps time scale. The B850 excited-state IR spectrum was found to differ substantially from that of B800, exhibiting a broader absorption band in the near-IR (centred at 1.1 mum) and new transient absorption features at 2.9 and 3.7 mum which are absent in B800. These results support a localised description of excitations for B800 but indicate the presence of considerably stronger inter-chromophore interactions between the B850 pigments. Differences between the excited-state spectra of B800 and B850 are interpreted as reflecting the formation of delocalized exciton and charge-resonance bands in B850. (C) 2001 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:121 / 126
页数:6
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