Kleima F J, Wendling M, Hofmann E, Peterman E J, van Grondelle R, van Amerongen H
Faculty of Sciences, Division of Physics and Astronomy, and Institute for Condensed Matter Physics and Spectroscopy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
Biochemistry. 2000 May 2;39(17):5184-95. doi: 10.1021/bi992427s.
Peridinin chlorophyll a protein (PCP) from Amphidinium carterae has been studied using absorbance (OD), linear dichroism (LD), circular dichroism (CD), fluorescence emission, fluorescence anisotropy, fluorescence line narrowing (FLN), and triplet-minus-singlet spectroscopy (T-S) at different temperatures (4-293 K). Monomeric PCP binds eight peridinins and two Chls a. The trimeric structure of PCP, resolved at 2 A [Hofmann et al. (1996) Science 27, 1788-1791], allows modeling of the Chl a-protein and Chl a-Chl a interactions. The FLN spectrum shows that Chl a is not or is very weakly hydrogen-bonded and that the central magnesium of the emitting Chl a is monoligated. Simulation of the temperature dependence of the absorption spectra indicates that the Huang-Rhys factor, characterizing the electron-phonon coupling strength, has a value of approximately 1. The width of the inhomogeneous distribution function is estimated to be 160 cm(-)(1). LD experiments show that the two Chls a in PCP are essentially isoenergetic at room temperature and that a substantial amount of PCP is in a trimeric form. From a comparison of the measured and simulated CD, it is concluded that the interaction energy between the two Chls a within one monomer is very weak, <10 cm(-)(1). In contrast, the Chls a appear to be strongly coupled to the peridinins. The 65 cm(-)(1) band that is visible in the low-frequency region of the FLN spectrum might indicate a Chl a-peridinin vibrational mode. The efficiency of Chl a to peridinin triplet excitation energy transfer is approximately 100%. On the basis of T-S, CD, LD, and OD spectra, a tentative assignment of the peridinin absorption bands has been made.
利用吸光度（OD）、线性二色性（LD）、圆二色性（CD）、荧光发射、荧光各向异性、荧光线宽变窄（FLN）以及三线态减单重态光谱（T-S），在不同温度（4 - 293K）下对来自卡氏扁藻（Amphidinium carterae）的多甲藻叶绿素a蛋白（PCP）进行了研究。单体PCP结合八个多甲藻素和两个叶绿素a。PCP的三聚体结构在2 Å分辨率下得以解析[霍夫曼等人（1996年）《科学》27卷，1788 - 1791页]，这使得对叶绿素a - 蛋白以及叶绿素a - 叶绿素a相互作用进行建模成为可能。FLN光谱表明叶绿素a没有或仅有非常微弱的氢键作用，并且发射荧光的叶绿素a的中心镁离子是单配位的。对吸收光谱温度依赖性的模拟表明，表征电子 - 声子耦合强度的黄 - 里斯因子的值约为1。非均匀分布函数的宽度估计为160 cm⁻¹。LD实验表明，PCP中的两个叶绿素a在室温下基本具有等能量，并且大量的PCP以三聚体形式存在。通过比较测量的和模拟的CD，得出结论：一个单体中两个叶绿素a之间的相互作用能非常弱，<10 cm⁻¹。相比之下，叶绿素a似乎与多甲藻素强烈耦合。在FLN光谱低频区域可见的65 cm⁻¹谱带可能表明存在叶绿素a - 多甲藻素振动模式。叶绿素a向多甲藻素三线态激发能量转移的效率约为100%。基于T-S、CD、LD和OD光谱，对多甲藻素吸收带进行了初步归属。
