Folding barrier in horse cytochrome c: support for a classical folding pathway.
Native-state structures and conformations of ferrocytochrome c, nitrosylcytochrome c, and carbonmonoxycytochrome c are very similar. They are, however, immensely different from each other in terms of thermodynamic stability. The dramatic destabilization of ferrocytochrome c to the extent of 12 kcal mol(-1) produces no effect on the folding rate, and this is so in spite of the fact that all three test-tube variants fold in an apparent two-state manner. For all three proteins the folding barrier is early in time, sizable in energy, and is of the same magnitude (approximately 6.5 kcal mol(-1)). These results raise some challenges to the "new view" of protein folding. An early transition state, the search for which consumes most of the observed folding time, is suggested.
School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
N Prakash
NP
Prabhu
Rajesh
R
Kumar
Abani K
AK
Bhuyan
D000818:Animals; D002248:Carbon Monoxide / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D019791:Guanidine / Q000737:chemistry; D006736:Horses; D009603:Nitroso Compounds / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D013816:Thermodynamics
D009603:Nitroso Compounds; D002248:Carbon Monoxide; D045304:Cytochromes c; D019791:Guanidine