Biophysical Chemistry Laboratory, CSIR-Indian Institute of Chemical Biology, Kolkata 700 032, India.
Chemosphere. 2012 May;87(7):775-81. doi: 10.1016/j.chemosphere.2011.12.079. Epub 2012 Feb 2.
The interaction of the phototoxic alkaloid coralyne with bovine and human serum albumins (BSA, HSA) was investigated. Absorbance and fluorescence quenching experiments revealed the formation of strong complexes. Based on the binding parameters calculated from Stern-Volmer quenching method, coralyne has higher affinity to BSA (10(5) M(-1)) compared to HSA (10(4) M(-1)). Forster resonance energy transfer studies showed that the specific binding distances between Trp (donor) of the proteins and coralyne (acceptor) were 2.95 and 3.10 nm, respectively. The bindings were favored by negative enthalpy and a stronger favorable entropy contribution. The heat capacity values for binding to BSA and HSA were similar, indicating the involvement of similar molecular forces in the complexation. Competitive binding experiments using site markers demonstrated that coralyne binds to site I (subdomain IIA) of both proteins. The secondary structure of the proteins was altered, suggesting a small but definitive partial unfolding on complexation.
研究了光毒生物碱石蒜碱与牛血清白蛋白（BSA）和人血清白蛋白（HSA）的相互作用。吸收和荧光猝灭实验表明形成了强复合物。基于 Stern-Volmer 猝灭法计算的结合参数，石蒜碱与 BSA（10(5) M(-1))的亲和力比 HSA（10(4) M(-1))更高。Förster 共振能量转移研究表明，蛋白质中色氨酸（供体）和石蒜碱（受体）之间的特定结合距离分别为 2.95 和 3.10nm。结合是由负焓和更强的有利熵贡献所驱动的。结合到 BSA 和 HSA 的热容值相似，表明在复合物形成中涉及相似的分子力。使用位点标记物进行的竞争性结合实验表明，石蒜碱结合到两种蛋白质的位点 I（亚域 IIA）。蛋白质的二级结构发生了改变，表明在复合物形成过程中发生了微小但明确的部分展开。
