Qy-excitation resonance Raman scattering from the special pair in Rhodobacter sphaeroides reaction centers. Implications for primary charge separation.
Qy-excitation resonance Raman scattering from the special pair in Rhodobacter sphaeroides reaction centers. Implications for primary charge separation.
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DOI：
10.1021/bi00160a014
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发表时间：
1992-11
期刊：
影响因子：
2.9
通讯作者：
V. Palaniappan;M. A. Aldema;H. Frank;D. Bocian
中科院分区：
文献类型：
--
作者：
V. Palaniappan;M. A. Aldema;H. Frank;D. Bocian
报道了类球红细菌2.4.1的反应中心的Qy激发共振拉曼（RR）光谱。通过使用在800-920 nm范围内的各种激发波长，在25和201 K下获得化学还原和氧化RC的RR光谱。该范围跨越特殊对（P）和辅助细菌叶绿素（BChls）的Qy吸收带。RR研究表明，P和副BChls在30-1800 cm ~（-1）区域都有丰富的RR谱。对于这两种类型的颜料，在30-750-cm-1范围内观察到至少20个谱带。虽然P和辅助BChls的模式的频率是不同的，它是可能的，使一对一的相关性的两种类型的色素所观察到的频带。这一结果表明，P的振动活性低频模式源自单体类振动（尽管它们可能是耦合的单体类模式），而不是由二聚体中存在的额外自由度引起的振动。一组合理的振动分配的低频模式的P和附件BChls的半经验正常坐标计算的基础上提出的。P的低频模式的RR强度与辅助BChls的类似模式的RR强度的比较表明，前者的模式的强度大大大于后者。总的来说，光谱数据表明，大量的低频模式的P强耦合到Qy电子跃迁。（250字处删节）
Qy-excitation resonance Raman (RR) spectra are reported for reaction centers (RCs) from Rhodobacter sphaeroides 2.4.1. The RR spectra were acquired for both chemically reduced and oxidized RCs at 25 and 201 K by using a variety of excitation wavelengths in the range 800-920 nm. This range spans the Qy absorption bands of the special pair (P) and the accessory bacteriochlorophylls (BChls). The RR studies indicate that both P and the accessory BChls exhibit rich RR spectra in the 30-1800-cm-1 region. For both types of pigments, at least 20 bands are observed in the 30-750-cm-1 range. Although the frequencies of the modes of P and the accessory BChls are different, it is possible to make one-to-one correlations of the bands observed for the two types of pigments. This result suggests that the vibronically active low-frequency modes of P are derived from monomer-like vibrations (although they may be coupled monomer-like modes) rather than being vibrations resulting from the additional degrees of freedom present in the dimer. A plausible set of vibrational assignments for the low-frequency modes of both P and the accessory BChls is proposed on the basis of a semiempirical normal coordinate calculation. Comparison of the RR intensities of the low-frequency modes of P with those of the analogous modes of the accessory BChls indicates that the intensities of the modes of the former pigments are considerably larger than those of the latter. Collectively, the spectral data indicate that a large number of low-frequency modes of P are strongly coupled to the Qy electronic transition.(ABSTRACT TRUNCATED AT 250 WORDS)