Chanphai P, Vesper A R, Bekale L, Bérubé G, Tajmir-Riahi H A
Department of Chemistry, Biochemistry and Physics, University of Québec at Trois-Rivières, C. P. 500, Trois-Rivières, QC G9A 5H7, Canada.
Department of Chemistry, Biochemistry and Physics, University of Québec at Trois-Rivières, C. P. 500, Trois-Rivières, QC G9A 5H7, Canada.
J Photochem Photobiol B. 2015 Dec;153:173-83. doi: 10.1016/j.jphotobiol.2015.09.008. Epub 2015 Sep 12.
A substantial part of steroids is bound to serum proteins in vivo. We report the association of testosterone and it aliphatic dimer (alip) and aromatic dimer (arom) with human serum albumin (HSA) and bovine serum albumin (BSA) in aqueous solution at physiological pH. Multiple spectroscopic methods, transmission electron microscopy (TEM) and molecular modeling were used to characterize steroid-protein binding and protein aggregation process. Spectroscopic analysis showed that steroids bind protein via hydrophobic, hydrophilic and H-bonding interactions. HSA forms more stable complexes than BSA. The binding affinity of steroid-protein adducts is testosterone>dimer-aromatic>dimer-aliphatic. Transmission electron microscopy showed major changes in protein morphology as steroid-protein complexation occurred with increase in the diameter of the protein aggregate indicating encapsulation of steroids by serum proteins. Modeling showed the presence of H-bonding stabilized testosterone-protein complexes with the free binding energy of -12.95 for HSA and -11.55 kcal/mol for BSA, indicating that the interaction process is spontaneous at room temperature. Steroid complexation induced more perturbations of BSA conformation than HSA.
在体内，相当一部分类固醇与血清蛋白结合。我们报道了睾酮及其脂肪族二聚体（alip）和芳香族二聚体（arom）在生理pH值的水溶液中与人类血清白蛋白（HSA）和牛血清白蛋白（BSA）的结合情况。使用了多种光谱方法、透射电子显微镜（TEM）和分子建模来表征类固醇 - 蛋白质结合及蛋白质聚集过程。光谱分析表明，类固醇通过疏水、亲水和氢键相互作用与蛋白质结合。HSA形成的复合物比BSA更稳定。类固醇 - 蛋白质加合物的结合亲和力为睾酮>二聚体 - 芳香族>二聚体 - 脂肪族。透射电子显微镜显示，随着类固醇 - 蛋白质复合作用的发生，蛋白质形态发生了重大变化，蛋白质聚集体直径增加，表明血清蛋白对类固醇进行了包裹。建模显示存在氢键稳定的睾酮 - 蛋白质复合物，其与HSA的自由结合能为 -12.95，与BSA的自由结合能为 -11.55千卡/摩尔，表明该相互作用过程在室温下是自发的。类固醇复合作用对BSA构象的扰动比对HSA的更大。
