Osmotic pressure induced coupling between cooperativity and stability of a helix-coil transition

Abstract

Most helix-coil transition theories can be characterized by a set of three parameters: energetic, describing the (free) energy cost of forming a helical state in one repeating unit; entropic, accounting for the decrease of entropy due to the helical state formation; and geometric, indicating how many repeating units are affected by the formation of one helical state. Depending on their effect on the helix-coil transition, solvents or co-solutes can be classified with respect to their action on these parameters. Solvent interactions that alter the entropic cost of helix formation by their osmotic action can affect both the stability (transition temperature) and the cooperativity (transition interval) of the helix-coil transition. A consistent inclusion of osmotic pressure effects in a description of helix-coil transition for poly(L-glutamic acid) in solution with polyethylene glycol can offer an explanation of the experimentally observed linear dependence of transition temperature on osmotic pressure as well as the concurrent changes in the cooperativity of the transition.

5 pages, 3 figures. To be submitted to Phys.Rev.Lett

References in corpus (4)

• Microscopic formulation of the Zimm-Bragg model for the helix-coil transition
• Competition for hydrogen bond formation in the helix-coil transition and protein folding
• Crowding effect on helix-coil transition: beyond entropic stabilization
• Solute Effects on the Helix-Coil Transition

Cited by in corpus (7)

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• A unified description of solvent effects in the helix-coil transition
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• Solvent Effects in the Helix-Coil Transition Model can explain the Unusual Biophysics of Intrinsically Disordered Proteins
• Potts Model with Invisible States: A Review
• Statistical mechanics of DNA-nanotube adsorption
• Ising model with invisible states on scale-free networks