The magnitude of changes in guanidine-HCl unfolding m-values in the protein, iso-1-cytochrome c, depends upon the substructure containing the mutation

Barbara Hammack, Kathleen Attfield, Daniel Clayton, Eric Dec, Aichun Dong, Catherine Sarisky, Bruce E. Bowler

Research output: Contribution to journalArticlepeer-review

Abstract

Hydrophilic to hydrophobic mutations have been made at 11 solvent exposed sites on the surface of iso-1-cytochrome c. Most of these mutations involve the replacement of lysine with methionine, which is nearly isosteric with lysine. Minimal perturbation to the native structure is expected, and this expectation is confirmed by infrared amide I spectroscopy. Guanidine hydrochloride denaturation studies demonstrate that these variants affect the magnitude of the m-value, the rate of change of free energy with respect to denaturant concentration, to different degrees. Changes in m-values are indicative of changes in the equilibrium folding mechanism of a protein. Decreases in m-values are normally thought to result either from an increased population of intermediates during unfolding or from a more compact denatured state. When cytochrome c is considered in terms of its thermodynamic substructures, the changes in the m-value for a given variant appear to depend upon the substructure in which the mutation is made. These data indicate that the relative stabilities and physical properties of substructures of cytochrome c play an important determining role in the equilibrium folding mechanism of this protein.

Original languageEnglish
Pages (from-to)1789-1795
Number of pages7
JournalProtein Science
Volume7
Issue number8
DOIs
StatePublished - 1998

Keywords

  • Equilibrium unfolding
  • Guanidine hydrochloride denaturation
  • Iso-1- cytochrome c
  • Protein substructures
  • m-values, protein stability

Fingerprint

Dive into the research topics of 'The magnitude of changes in guanidine-HCl unfolding m-values in the protein, iso-1-cytochrome c, depends upon the substructure containing the mutation'. Together they form a unique fingerprint.

Cite this