Infrared spectroelectrochemistry of bacteriochlorophylls and bacteriopheophytins: Implications for the binding of the pigments in the reaction center from photosynthetic bacteria.
Infrared spectroelectrochemistry of bacteriochlorophylls and bacteriopheophytins: Implications for the binding of the pigments in the reaction center from photosynthetic bacteria.
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DOI：
10.1073/pnas.85.22.8468
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发表时间：
1988-11
影响因子：
11.1
通讯作者：
W. Mäntele;A. Wollenweber;E. Nabedryk;J. Breton
中科院分区：
文献类型：
--
作者：
W. Mäntele;A. Wollenweber;E. Nabedryk;J. Breton
利用红外光谱和光学透明电化学池获得了细菌叶绿素a和B阳离子以及细菌脱镁叶绿素a和B阴离子的红外光谱。自由基形成的振动光谱上的显着影响被发现的频带分配到酯，酮，和乙酰基C=O基团和大环键的振动。的（自由基减去中性）的差异光谱相比，光诱导的差异光谱的主要供体光氧化和中间受体光还原的光合细菌的反应中心。从含细菌叶绿素a的反应中心的光诱导的吸光度变化承担惊人的相似性，电化学诱导的吸光度变化后观察到的细菌叶绿素a（+）在体外形成。在氢键或非氢键溶剂中体外自由基形成的比较表明酯C=O基团在中性状态下氢键键合，但在阳离子状态下是游离的。对于酮基C=O基团，相同的比较表明一个游离羰基。细菌脱镁叶绿素a和B的（阴离子-中性）差谱在酯C=O频率范围内呈现单一谱带。与此相反，在中间受体还原反应中心的绿色红球藻的差谱中观察到两个带。较高的频带表现出对（1）H-（2）H交换的敏感性，这表明来自氨基酸侧链的质子化羧基的贡献。
The IR spectra of the bacteriochlorophyll a and b cations and the bacteriopheophytin a and b anions were obtained by using an IR and optically transparent electrochemical cell. Prominent effects of radical formation on the vibrational spectra were found for bands assigned to the ester, keto, and acetyl C=O groups and for vibrations from macrocycle bonds. The (radical-minus-neutral) difference spectra are compared to the light-induced difference spectra of the primary donor photooxidation and the intermediary acceptor photoreduction in the reaction center of photosynthetic bacteria. Light-induced absorbance changes from bacteriochlorophyll a-containing reaction centers bear striking similarities to the electrochemically induced absorbance changes observed upon formation of bacteriochlorophyll a(+)in vitro. Comparison of the radical formation in vitro in a hydrogen-bonding or a nonhydrogen-bonding solvent suggests an ester C=O group hydrogen bonded in the neutral state but free in the cation state. For the keto C=O group, the same comparison indicates one free carbonyl group. The (anion-minus-neutral) difference spectra of bacteriopheophytin a and b exhibit a single band in the ester C=O frequency range. In contrast, two bands are observed in the difference spectra of the intermediary acceptor reduction in the reaction center of Rhodopseudomonas viridis. The higher frequency band exhibits a sensitivity to (1)H-(2)H exchange, which suggests a contribution from a protonated carboxyl group of an amino acid side chain.