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.
Prabhu
N Prakash
NP
School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
Kumar
Rajesh
R
Bhuyan
Abani K
AK
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