Demidov A A
Physics Department of Moscow State University, Russia.
Biophys J. 1994 Dec;67(6):2184-90. doi: 10.1016/S0006-3495(94)80704-0.
A new method is presented for calculation of the fluorescence depolarization and kinetics of absorption anisotropy for molecular complexes with a limited number of chromophores. The method considers absorption and emission of light by both chromophores, and also energy transfer between them, with regard to their mutual orientations. The chromophores in each individual complex are rigidly positioned. The complexes are randomly distributed and oriented in space, and there is no energy transfer between them. The new "practical" formula for absorption anisotropy and fluorescence depolarization kinetics, P(t) = [3B(t) - 1 + 2A(t)]/[3 + B(t) + 4A(t)], is derived both for double- and triple-chromophore complexes with delta-pulse excitation. The parameter B(t) is given by (a) B(t) = cos2(theta) for double-chromophore complexes, and (b) B(t) = q12(t)cos2(theta 12) + q13(t)-cos2(theta 13) + q23(t)cos2(theta 23) for triple-chromophore complexes, where q12(t) + q13(t) + q23(t) = 1. Here theta ij are the angles between the chromophore transition dipole moments in the individual molecular complex. The parameters qij(t) and A(t) are dependent on chromophore spectroscopic features and on the rates of energy transfer.
提出了一种新方法，用于计算具有有限数量发色团的分子复合物的荧光去极化和吸收各向异性动力学。该方法考虑了两个发色团对光的吸收和发射，以及它们之间的能量转移，并考虑了它们的相互取向。每个单独复合物中的发色团都处于固定位置。复合物在空间中随机分布和取向，它们之间不存在能量转移。针对具有δ脉冲激发的双发色团和三发色团复合物，推导了吸收各向异性和荧光去极化动力学的新“实用”公式，即P(t)=[3B(t)-1 + 2A(t)]/[3 + B(t)+4A(t)]。参数B(t)由以下给出：(a)对于双发色团复合物，B(t)=cos2(θ)；(b)对于三发色团复合物，B(t)=q12(t)cos2(θ12)+q13(t)cos2(θ13)+q23(t)cos2(θ23)，其中q12(t)+q13(t)+q23(t)=1。这里θij是单个分子复合物中发色团跃迁偶极矩之间的夹角。参数qij(t)和A(t)取决于发色团的光谱特征和能量转移速率。
