title: Salt effects on protein stability: two-stranded alpha-helical coiled-coils containing inter- or intrahelical ion pairs.
abstract: An investigation into the role of surface-accessible ion pairs in protein stability was carried out by determining the effects of added salt (KCl, MgCl2 and LaCl3) at neutral and acidic pH on the stability of de novo designed two-stranded alpha-helical coiled-coils. The effects of salt on the stability of coiled-coils containing interhelical i to i' + 5 or intrahelical i to i + 4 and i to i + 3 Lys-Glu ion pairs were compared to the effects on the stability of a control coiled-coil, which contained no intra- or interhelical ion pair. These studies indicate that ionic interactions contribute to coiled-coil stability. The results show that added salt can have complex effects on protein stability, involving stabilizing and destabilizing contributions with the net effect depending on the nature of the charged residues and ionic interactions present in the protein.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Canada.
authors.forename: W D
authors.initials: WD
authors.lastname: Kohn
authors.forename: C M
authors.initials: CM
authors.lastname: Kay
authors.forename: R S
authors.initials: RS
authors.lastname: Hodges
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007811:Lanthanum / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010455:Peptides / Q000737:chemistry* / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011489:Protein Denaturation; D017433:Protein Structure, Secondary / Q000187:drug effects*; D012492:Salts / Q000494:pharmacology*
chemical_list: D007477:Ions; D010455:Peptides; D012492:Salts; D015636:Magnesium Chloride; C028521:lanthanum chloride; D011189:Potassium Chloride; D007811:Lanthanum