title: Effects of alcohol on the solubility and structure of native and disulfide-modified bovine serum albumin.
abstract: Differential precipitation of human plasma by ethanol is one of the most important processes for purifying therapeutic proteins, including human serum albumin. Better understanding of the effects of ethanol on the structure and stability of proteins is critical for effective and safe application of ethanol-induced protein precipitation. Here, we examined the effects of ethanol on the structure and solubility of bovine serum albumin (BSA) and SH-modified BSA. Ethanol caused BSA denaturation in a bimodal fashion, i.e., reduction of α-helix at low concentration and subsequent induction of the α-helical structure at higher concentration. In contrast, the solubility of BSA decreased monotonically. The secondary structure of SH-modified BSA was different from that of native BSA. Ethanol resulted in enhanced secondary structures of SH-modified BSA and decreased solubility monotonically. These results suggest the favorable interaction of ethanol with hydrophobic residues, leading to protein denaturation, but the unfavorable interaction with charged residues, leading to a reduction of protein solubility.
authors.affiliation: Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirano
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Arakawa
authors.forename: Kentaro
authors.initials: K
authors.lastname: Shiraki
mesh_terms: D000438:Alcohols / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D004220:Disulfides / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012995:Solubility / Q000187:drug effects; D014867:Water / Q000737:chemistry
chemical_list: D000438:Alcohols; D004220:Disulfides; D014867:Water; D012710:Serum Albumin, Bovine; D000431:Ethanol