Electrochemical evidence for the molten globule states of cytochrome c induced by N-alkyl sulfates at low concentrations

J Protein Chem. 2003 Jan;22(1):23-30. doi: 10.1023/a:1023011609931.

Abstract

The molten globule state (MG) of cytochrome c is the major intermediate of protein folding. The formation of MG state of cytochrome c is induced by n-alkyl sulfates such as sodium octyl sulfate (SOS), sodium dodecyl sulfate (SDS), and sodium tetradecyl sulfate (STS). The folding state of cytochrome c was monitored using circular dichroism (CD), isothermal titration calorimetry (ITC) and partial specific volumes. To explore a new approach for characterizing the MG conformation, cyclic voltametric studies of n-alkyl sulfates induced transition at acidic pH of cytochrome c (unfolded state, U) was carried out. Here, we have used a cystein-modified gold electrode, which is effective for direct rapid electron transfer to cytochrome c even in acid solutions, to directly observe electrochemistry in native (N) cytochrome c. Our results show that the extent of electron transfer is increased for U --> MG, and also the easiness of electron transferring occurred from MG --> N transition. Thus we demonstrate that the MG state of cytochrome c, induced by n-alkyl sulfates as salts with hydrophobic chains (hydrophobic salts), with different compactness reaches to near identical amount of electron transferring as N state.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calorimetry
  • Circular Dichroism
  • Cytochrome c Group / chemistry*
  • Electrochemistry
  • Horses
  • Myocardium / chemistry
  • Protein Conformation
  • Protein Folding*
  • Sulfuric Acid Esters / chemistry*

Substances

  • Cytochrome c Group
  • Sulfuric Acid Esters