Perera N L Dilani, Betancourt Jovany, Miksovska Jaroslava, O'Shea Kevin E
Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8 Street, Miami, FL 33199, United States.
Curr Res Toxicol. 2023 Oct 3;5:100130. doi: 10.1016/j.crtox.2023.100130. eCollection 2023.
Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are often referred to as legacy perfluoroalkyl substances (PFAS). Human exposure to PFAS leads to severe negative health impacts including cancers, infertility, and dysfunction in the kidneys. Steady-state absorbance, fluorescence, and circular dichroism (CD) methods were used to study the interactions between PFOA and Hb. The results demonstrate the presence of multiple PFOA binding sites on the Hb protein. The detailed analysis of the ferric hemoglobin protein (met Hb) absorbance data as a function of PFOA concentration indicates the presence of at least two binding sites with equilibrium dissociation constants of 0.8 ± (0.2) × 10 M and 63 ± (15) × 10 M. A competitive binding study with 1,8-ANS showed PFOA can bind to the same binding site as 1,8-ANS on the Hb protein. The titration curve for PFOA binding to Hb in its CO bound form (CO-Hb) yields a single equilibrium dissociation constant of 139 ± (20) × 10 M. PFOA binding at low concentrations occurs at the high-affinity sites leading to the destabilization of the protein structure as reflected by changes in the CD spectrum. PFOA interactions with Hb also interfere with the kinetics of CO association to this protein. The rate for CO association to Hb increases at low PFOA concentrations, whereas at elevated PFOA concentrations, the ligand association is biphasic as a new kinetic process with a different rate constant was observed. Overall, this study provides a detailed explanation of PFOA-induced structural and conformational changes to the Hb protein based on the spectroscopy data.
全氟辛酸（PFOA）和全氟辛烷磺酸（PFOS）通常被称为遗留全氟烷基物质（PFAS）。人类接触PFAS会导致严重的负面健康影响，包括癌症、不孕以及肾脏功能障碍。采用稳态吸光度、荧光和圆二色性（CD）方法研究了PFOA与血红蛋白（Hb）之间的相互作用。结果表明Hb蛋白上存在多个PFOA结合位点。对高铁血红蛋白蛋白（met Hb）吸光度数据作为PFOA浓度函数的详细分析表明，存在至少两个结合位点，其平衡解离常数分别为0.8 ±（0.2）× 10⁻⁶ M和63 ±（15）× 10⁻⁶ M。与1,8 - 苯胺基萘磺酸（1,8 - ANS）的竞争性结合研究表明，PFOA可与1,8 - ANS在Hb蛋白上结合到相同的结合位点。PFOA与一氧化碳结合形式的Hb（CO - Hb）结合的滴定曲线得出单一平衡解离常数为139 ±（20）× 10⁻⁶ M。低浓度下PFOA的结合发生在高亲和力位点，导致蛋白质结构不稳定，这在CD光谱变化中得到反映。PFOA与Hb的相互作用也会干扰一氧化碳与该蛋白结合的动力学。一氧化碳与Hb结合的速率在低PFOA浓度下增加，而在高PFOA浓度下，配体结合是双相的，因为观察到了具有不同速率常数的新动力学过程。总体而言，本研究基于光谱数据对PFOA诱导的Hb蛋白结构和构象变化提供了详细解释。
