Paillotin G, Breton J
Biophys J. 1977 Apr;18(1):63-79. doi: 10.1016/S0006-3495(77)85597-5.
The effects on the optical properties of photosynthetic membranes caused by several types of chlorophyll differing in resonance frequency and in spatial disposition are theoretically analyzed. Using a method of moments and the linear dichroism spectrum of the lamellae, we evaluated the mean angle (phi) between the transition moment of each chlorophyll and the normal to the lamellae. We have confirmed that at about 695 nm the transition moment is in the plane of the lamellae, and outside it for chlorophyll b (phi approximately 48.6 degrees). By integrating over frequency the absorption variations affected by ionophores, we show that they may be ascribed to a Stark effect, and we analyze the dependence of this effect on the orientation of the chlorophylls. From this dependence and the degree of polarization of the Stark effect, we calculate the spatial fluctuations of the angle phi. The calculation shows that a definite value of phi corresponds to each resonance frequency of chlorophyl a found in vivo. This proves that the chlorophylls a are not oriented partly random. For chlorophylls b, on the other hand, phi may fluctuate by some 10 degrees about its mean value. The structural consequences of these results are discussed.
从理论上分析了几种在共振频率和空间分布上存在差异的叶绿素对光合膜光学性质的影响。利用矩量法和片层的线性二向色性光谱，我们评估了每种叶绿素的跃迁矩与片层法线之间的平均夹角（φ）。我们已经证实，在约695nm处，跃迁矩位于片层平面内，而叶绿素b的跃迁矩则在片层平面外（φ约为48.6度）。通过对受离子载体影响的吸收变化进行频率积分，我们表明这些变化可归因于斯塔克效应，并分析了该效应与叶绿素取向的相关性。根据这种相关性以及斯塔克效应的极化程度，我们计算了夹角φ的空间波动。计算结果表明，体内发现的叶绿素a的每个共振频率都对应一个确定的φ值。这证明叶绿素a并非部分随机取向。另一方面，对于叶绿素b，φ可能会围绕其平均值波动约10度。讨论了这些结果的结构意义。
