title: Kinetic equivalence of the heat and cold structural transitions of lambda6-85.
abstract: Heat- and cold-denatured proteins are considered separate thermodynamic states because temperature tuning requires the protein to pass through two 'soft' first-order phase transitions. When both pressure and temperature changes are allowed, the heat- and cold-denatured states of proteins can be interconverted without going through the native state. This raises the question of whether these states are distinguished from one another by their folding kinetics. For the Tyr22Trp/Ala37Gly/Ala49Gly mutant of the 80 residue five-helix bundle protein lambda(6-85), we show that viscosity-corrected folding rates do not distinguish the cold- and heat-denatured states. We attribute this to a folding mechanism dominated by hydrophobic collapse. Our 'temperature-symmetric' approach offers an alternative to viscosity tuning with solvent additives in such cases.
authors.affiliation: Center for Biophysics and Computational Biology, and Department of Chemistry, University of Illinois, Urbana, IL 61801, USA.
authors.forename: Wei Y
authors.initials: WY
authors.lastname: Yang
authors.forename: Martin
authors.initials: M
authors.lastname: Gruebele
mesh_terms: D003080:Cold Temperature; D003198:Computer Simulation; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000737:chemistry*; D006358:Hot Temperature; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D009038:Motion; D044367:Phase Transition; D011312:Pressure; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000032:analysis* / Q000737:chemistry*; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins