Competitive binding of aqueous perfluoroctanesulfonic acid and ibuprofen with bovine serum albumin studied by electrospray ionization mass spectrometry

Serum albumin binds reversibly with and transports endogenous and exogenous ligands, such as pharmaceuticals, whose therapeutic efficacy is activated upon liberation from the protein. Aqueous perfluoroctanesulfonic acid is a bioaccumulative, pervasive species of anthropogenic origin found in the serum of 90% of Americans that adventitiously binds with high affinity to serum albumin in the same specific site as ibuprofen; thus the conditions for competitive binding are established. This study investigated the competitive interaction between aqueous perfluoroctanesulfonic acid and ibuprofen in binding to bovine serum albumin (BSA) using electrospray ionization mass spectrometry. Perfluoroctanesulfonate was found to displace all bound ibuprofen from BSA and to prevent further ibuprofen binding when the fluorinated analyte concentration exceeds half that of ibuprofen. These observations imply that perfluo-roctanesulfonate may displace ibuprofen and similar pharmaceuticals from serum albumin in the body under physiological conditions thus altering the pharmacokinetics and deposition of such drugs. (C) 2012 Elsevier B.V. All rights reserved.