Querying the In Vitro Proteome Cysteine Reactivity of 8:2 Fluorotelomer Acrylate

Despite the phase out of legacy per- and polyfluoroalkyl substances (PFAS), fluorotelomer-based polymers (FTP) have been used for many applications, notably textile surface coatings. FTPs are of a health concern due to their breakdown into legacy PFAS and the co-occurrence of fluorotelomer acrylate (FTAC) monomers, of which the latter may potentially react with cellular thiols. To evaluate this hypothesis, we employed fluorous-solid-phase extraction (FSPE), to enrich peptides covalently modified by 8:2 fluorotelomer acrylate (8:2 FTAC) and coupled it to a modified nano-liquid chromatography method for the identification of in vitro protein adducts using bottom-up data-dependent proteomics analysis. Using this method, over 100 unique peptides were detected with 8:2 FTAC modifications, although none of the modified cysteine residues were annotated active site nucleophiles. In parallel, a synthetic C6F13-iodoacetamide (F-13-IAM) chemical probe was used to gauge the upper bound of PFAS-thiol reactivity. Over seven hundred peptides were detected with modifications but only 9 of 28 annotated active site cysteines in this dataset were modified by F-13-IAM. Further exploration of the impacts of 8:2 FTAC adducts on protein function revealed that 8:2 FTAC modification promotes protein aggregation in vitro. These results suggest that 8:2 FTAC may exhibit significant proteome thiol reactivity and imply a more general mechanism of toxicity of PFAS-induced protein aggregation.

Automated summary

Despite the phase out of legacy PFAS, FTPs are still used for textile surface coatings and raise health concerns due to breakdown into legacy PFAS and co-occurrence of FTAC. This study used FSPE and nano-liquid chromatography to detect 8:2 FTAC modifications on peptides, revealing potential thiol reactivity but no active site nucleophiles. Additionally, the study found that 8:2 FTAC modifications promote protein aggregation in vitro, suggesting a general mechanism of PFAS-induced toxicity.