Laia César A T, Costa Sílvia M B
Centro de Química-Estrutural, Complexo 1, Instituto Superior Técnico, 1049-001 Lisboa, Portugal.
J Phys Chem B. 2008 Apr 10;112(14):4276-82. doi: 10.1021/jp076100+. Epub 2008 Mar 19.
The interaction of a zinc tetrasulfonated phthalocyanine with cytochrome c was studied using steady-state spectroscopic techniques and time-correlated single photon counting in water and Triton-X 100 micelles. The dye forms dimers in water with a high equilibrium constant (70 x 10(6) M(-1)). Because of a specific electrostatic interaction, the presence of cytochrome c does not lead to a dissociation of this dimer, but increases its formation, with an equilibrium constant of about 7.9 x 10(9) M(-1). Triton-X 100 micelles dissociate the dimer, creating two populations of dye molecules: one in a hydrophilic media, probably on the surface of the micelles, another on a hydrophobic environment, probably inside the micelles. However, when cytochrome c is added the dye aggregation is again induced leading to a strong fluorescence quenching. This fluorescence quenching may also be caused by a photoinduced electron-transfer due to the formation of a 1:1 complex between the dye and the protein, but the present work does not give direct evidence of such an effect because the fluorescence decays did not show the presence of an extra component. The results presented here are quite different from those reported for aluminum sulfonated phthalocyanines, where aggregation does not occur and the fluorescence quenching is solely due to photoinduced electron-transfer reactions.
采用稳态光谱技术和时间相关单光子计数法，研究了四磺酸锌酞菁在水和Triton-X 100胶束中与细胞色素c的相互作用。该染料在水中形成二聚体，平衡常数较高（70×10⁶ M⁻¹）。由于特定的静电相互作用，细胞色素c的存在不会导致该二聚体解离，反而会增加其形成，平衡常数约为7.9×10⁹ M⁻¹。Triton-X 100胶束会使二聚体解离，产生两类染料分子：一类处于亲水性介质中，可能在胶束表面；另一类处于疏水环境中，可能在胶束内部。然而，加入细胞色素c后，染料再次发生聚集，导致强烈的荧光猝灭。这种荧光猝灭也可能是由于染料与蛋白质形成1:1复合物而引发的光诱导电子转移所致，但本研究并未给出这种效应的直接证据，因为荧光衰减并未显示存在额外成分。此处呈现的结果与磺化铝酞菁的报道结果截然不同，在磺化铝酞菁中不会发生聚集，荧光猝灭 solely 是由光诱导电子转移反应引起的。 （注：solely 原英文拼写有误，这里按正确的意思翻译）
