Binding of Perfluorocarboxylates to Serum Albumin: A Comparison of Analytical Methods

摘要

Perfluorochemicals are globally pervasive contaminantsnthat are persistent, bioaccumulative, and toxic. Perfluorocarboxylicnacids (PFCAs) with 8-13 carbons accumulatenin the liver and blood of aquatic organisms; PFCAproteinninteractions may explain this accumulation pattern.nHere, the interactions between PFCAs with 8-11ncarbons and serum albumin are examined using threenexperimental approaches: surface tension titrations, 19FnNMR spectroscopy, and fluorescence spectroscopy.nSurface tension titrations indicate complex formationnat high (mM) PFCA concentrations. Secondary associationnconstants ranging from 102 to 104 M-1 werendetermined from 19F NMR titrations at high PFCA:nalbumin mole ratios. Fluorescence measurementsnindicate that PFCA-albumin interactions alter thenprotein conformation at low PFCA:albumin mole ratiosn(up to 5:1) and suggest two binding classes withnassociation constants around 105 and 102 M-1. Whilen19F NMR and fluorescence provide both qualitative andnquantitative information about PFCA-albumin interactions,nsurface tension provides only qualitative information.nLimitations associated with instrumentationnand methods require high PFCA concentrations in bothnsurface tension and 19F NMR experiments; in contrast,nfluorescence allows for analysis of a wider range ofnPFCA concentrations and PFCA:albumin mole ratios.nResults from this study indicate that fluorescence, thoughnan indirect method, offers a more comprehensive picturenof the nature of PFCA-albumin interactions.