Complex ion effects on polypeptide conformational stability: Chloride and sulfate salts of guanidinium and tetrapropylammonium

C.E Dempsey, P.E Mason, P Jungwirth

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Citations (Scopus)

Abstract

The effects of chloride and sulfate salts of tetrapropylammonium (TPA+) and guanidinium (Gdm+) on the conformational stabilities of tryptophan zipper (trpzip) and α-helical (alahel) peptides were measured by circular dichroism spectroscopy. Like Gdm+, TPA+ interacts with the planar tryptophan indole group, perturbing the conformational stability of trpzip peptides. TPA+ effects are largely unaffected by sulfate, indicating an absence of the heteroion pairing that is observed in concentrated Gdm2SO4 solutions. TPA+ stabilizes helical conformations in alahel peptides, indicating exclusion from the peptide bond. The observations are broadly consistent with predictions of molecular dynamics simulations [Mason, P. E.; et al. J. Phys. Chem. B2009, 113, 3227–3234], indicating that the effects of complex ions on proteins are increasingly predictable in terms of ion hydration, complementary interactions with specific protein groups, and ion-pairing contributions.
Translated title of the contributionComplex ion effects on polypeptide conformational stability: Chloride and sulfate salts of guanidinium and tetrapropylammonium
Original languageEnglish
Pages (from-to)7300 - 7303
Number of pages4
JournalJournal of the American Chemical Society
Volume133 (19)
DOIs
Publication statusPublished - May 2011

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