Table . Summary of major mechanisms suggested for the action of denaturants on protein stability Denaturant Direct/ Molecular mechanism Experimental Reference indirect suggested or simulation interaction Interactions with hydrophobic surfaces on protein Guanidinium Direct Guanidinium is dehydrated Simulation (England et al. along planar face and lines 2008) up flat along hydrophobic surface, weakening hydrophobic effect Guanidinium Direct Coating of hydrophobic Simulation (Godawat et al. surfaces, weakening 2010) hydrophobic effect Urea Direct & Urea interacts favourably Simulation (Stumpe & Indirect with hydrophobic side Grubmüller chains and peptide 2007b; Stumpe backbone. It also & Grubmüller strengthens water-water 2007a) interactions Urea Direct Transiently aggregates near Simulation (Zangi et al. hydrophobic surfaces 2009) Urea & Direct Direct binding to specific Experimental (Makhatadze & Guanidinium sites on protein normally (Calorimetry) Privalov 1992) occupied by water
Table . Summary of major mechanisms suggested for the action of denaturants on protein stability Denaturant Direct/ indirect interaction Molecular mechanism suggested Experimental or simulation Reference Interactions with hydrophobic surfaces on protein Guanidinium Direct Guanidinium is dehydrated along planar face and lines up flat along hydrophobic surface, weakening hydrophobic effect Simulation (England et al. 2008) Guanidinium Direct Coating of hydrophobic surfaces, weakening hydrophobic effect Simulation (Godawat et al. 2010) Urea Direct & Indirect Urea interacts favourably with hydrophobic side chains and peptide backbone. It also strengthens water-water interactions Simulation (Stumpe & Grubmüller 2007b; Stumpe & Grubmüller 2007a) Urea Direct Transiently aggregates near hydrophobic surfaces Simulation (Zangi et al. 2009) Urea & Guanidinium Direct Direct binding to specific sites on protein normally occupied by water Experimental (Calorimetry) (Makhatadze & Privalov 1992)