Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, 69 N Eagleville Road, Unit 3092, Storrs, CT 06269, USA.
Int J Pharm. 2012 Dec 15;439(1-2):317-23. doi: 10.1016/j.ijpharm.2012.09.013. Epub 2012 Sep 15.
Binding of a surfactant to proteins can affect their physicochemical stability and solubility in a formulation. The extent of the effect depends on the binding stoichiometry. In this study, we have utilized the technique of maximum bubble pressure surface tensiometry to characterize the binding between human serum albumin (HSA) and surfactants (sodium dodecyl sulfate (SDS) and polysorbate 80) by dynamic surface tension measurements. Results show that two classes of binding sites are present in HSA for SDS, 5 primary binding sites with high binding affinity (K(a)=5.38×10(5) M(-1)) and 12 secondary binding sites with low affinity (K(a)=6.7×10(4) M(-1)). The binding is high affinity and limited capacity due to both, ionic and hydrophobic interactions between HSA and SDS. For polysorbate 80, the binding does not follow the Scatchard plot, and is low affinity and high capacity, indicating that polysorbate 80 interacts with HSA through hydrophobic interactions. The results show that maximal bubble pressure surface tensiometry is a fast and convenient technique to determine the concentration of free and bound surfactants in the presence of proteins.
表面活性剂与蛋白质的结合会影响其在配方中的理化稳定性和溶解度。这种影响的程度取决于结合的化学计量比。在这项研究中，我们利用最大气泡压力表面张力法，通过动态表面张力测量来表征人血清白蛋白（HSA）与表面活性剂（十二烷基硫酸钠（SDS）和聚山梨酯 80）之间的结合。结果表明，SDS 在 HSA 中有两类结合位点，5 个高亲和力的主要结合位点（K(a)=5.38×10(5) M(-1)）和 12 个低亲和力的次要结合位点（K(a)=6.7×10(4) M(-1)）。由于 HSA 和 SDS 之间的离子和疏水相互作用，结合是高亲和力和有限容量的。对于聚山梨酯 80，结合不符合 Scatchard 图，并且是低亲和力和高容量的，表明聚山梨酯 80 通过疏水相互作用与 HSA 相互作用。结果表明，最大气泡压力表面张力法是一种快速方便的技术，可以在存在蛋白质的情况下确定游离和结合表面活性剂的浓度。
