Inhaled anesthetics affect protein-protein interaction, but the mechanisms underlying these effects are still poorly understood. We examined the impact of sevoflurane and isoflurane on the dimerization of human serum albumin (HSA), a protein with anesthetic binding sites that are well characterized. Intrinsic fluorescence emission was analyzed for spectral shifting and self-quenching, and control first derivatives (spectral responses to changes in HSA concentration) were compared against those obtained from samples treated with sevoflurane or isoflurane. Sevoflurane increased dimer-dependent self-quenching and both decreased oligomer-dependent spectral shifting, suggesting that inhaled anesthetics promoted HSA dimerization. Size exclusion chromatography and polarization data were consistent with these observations. The data support the proposed model of a reciprocal exchange of subdomains to form an HSA dimer. The open-ended exchange of subdomains, which we propose occuring in HSA oligomers, was inhibited by sevoflurane and isoflurane.

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We examined the effects of air-water and water-sevoflurane interfaces on conformational properties of amyloid-beta peptide (ABP). Fractions were extracted from sub-interfacial (air-water) and supra-interfacial (water-sevoflurane) layers and compared with aqueous bulk layers using fluorescence properties of ABP provided by a single tyrosine. The observations suggest that interfacial ABP may be more disordered than bulk ABP.