Author(s): Moosavi-Movahedi AA, Chamani J, Ghourchian H, Shafiey H, Sorenson CM, Sheibani N. 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. PMID 12739895
Journal: Journal Of Protein Chemistry, Volume 22, Issue 1, Jan 2003
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.