两亲性酞菁锌与牛血清白蛋白结合的研究

Combining Interaction of Amphiphilic Phthalocyanine Zinc with Bovine Serum Albumin

二磺基二邻苯二甲酰亚胺甲基酞菁锌 (ZnPcS2 P2 )是一种具有光动力活性的两亲性抗癌光敏剂 ,本文应用紫外吸收示差光谱、稳态和动态荧光光谱及平衡透析法研究了在生理条件下ZnPcS2 P2 与牛血清白蛋白(BSA)之间的相互作用。基于Hill位点模型 ,应用改进的蛋白内源荧光猝灭法求得ZnPcS2 P2 与BSA形成复合物的结合参数 ,结果与平衡透析法基本一致。

The di-sulfo, di-plithalimidomethyl-zinc phthalolcyanine (ZnPcS2P2), which has the photodynamic activities against tumors as amphiphilic photosensitizer for photodynamic therapy, is transported by the blood circulatory system to target tissues. In this paper, the interaction of phthalocyanine with bovine serum albumin (BSA) has been investigated using absorption and differential absorption spectra, steady-state and time-resolved fluorescence spectra as well as equilibrium dialysis. The results show that ZnPcS2P2 molecules are combined to BSA mainly in monomer fashion. Addition of ZnPcS2P2 results in the conformational changes of BSA. Based on the Hill plot model, an improving method of quenching albumin intrinsic tryptophan fluorescence, which supported the cooperative binding of ZnPcS2P2 with BSA, was applied. ZnPcS2P2 occupies one strong binding site and four weaker sites, the binding constant K is 3.2x10(5) L/mol and 2.0x10(5) L/mol respectively. The binding constants are consistent with those obtained by equilibrium dialysis.