Department of Chemistry, Union College, Schenectady, New York 12308, USA.
Anal Chem. 2010 Feb 1;82(3):974-81. doi: 10.1021/ac902238u.
Perfluorochemicals are globally pervasive contaminants that are persistent, bioaccumulative, and toxic. Perfluorocarboxylic acids (PFCAs) with 8-13 carbons accumulate in the liver and blood of aquatic organisms; PFCA-protein interactions may explain this accumulation pattern. Here, the interactions between PFCAs with 8-11 carbons and serum albumin are examined using three experimental approaches: surface tension titrations, (19)F NMR spectroscopy, and fluorescence spectroscopy. Surface tension titrations indicate complex formation at high (mM) PFCA concentrations. Secondary association constants ranging from 10(2) to 10(4) M(-1) were determined from (19)F NMR titrations at high PFCA:albumin mole ratios. Fluorescence measurements indicate that PFCA-albumin interactions alter the protein conformation at low PFCA:albumin mole ratios (up to 5:1) and suggest two binding classes with association constants around 10(5) and 10(2) M(-1). While (19)F NMR and fluorescence provide both qualitative and quantitative information about PFCA-albumin interactions, surface tension provides only qualitative information. Limitations associated with instrumentation and methods require high PFCA concentrations in both surface tension and (19)F NMR experiments; in contrast, fluorescence allows for analysis of a wider range of PFCA concentrations and PFCA:albumin mole ratios. Results from this study indicate that fluorescence, though an indirect method, offers a more comprehensive picture of the nature of PFCA-albumin interactions.
全氟化学品是全球性的污染物，具有持久性、生物蓄积性和毒性。具有 8-13 个碳原子的全氟羧酸（PFCAs）在水生生物的肝脏和血液中积累；PFCA-蛋白质相互作用可能解释了这种积累模式。在这里，使用三种实验方法研究了具有 8-11 个碳原子的 PFCAs 与血清白蛋白之间的相互作用：表面张力滴定、（19）F NMR 光谱和荧光光谱。表面张力滴定表明在高（mM）PFCAs 浓度下形成复合物。从高 PFCAs:白蛋白摩尔比的（19）F NMR 滴定中确定了二级缔合常数范围为 10（2）至 10（4）M（-1）。荧光测量表明，PFCAs-白蛋白相互作用在低 PFCAs:白蛋白摩尔比（高达 5:1）下改变蛋白质构象，并表明两种结合类，其缔合常数约为 10（5）和 10（2）M（-1）。虽然（19）F NMR 和荧光提供了关于 PFCAs-白蛋白相互作用的定性和定量信息，但表面张力仅提供定性信息。与仪器和方法相关的限制要求在表面张力和（19）F NMR 实验中使用高 PFCAs 浓度；相比之下，荧光允许分析更广泛的 PFCAs 浓度和 PFCAs:白蛋白摩尔比范围。这项研究的结果表明，尽管荧光是一种间接方法，但它提供了更全面的 PFCAs-白蛋白相互作用性质的图片。
