title: Competition for hydrogen-bond formation in the helix-coil transition and protein folding.
abstract: The problem of the helix-coil transition of biopolymers in explicit solvents, such as water, with the ability for hydrogen bonding with a solvent is addressed analytically using a suitably modified version of the Generalized Model of Polypeptide Chains. Besides the regular helix-coil transition, an additional coil-helix or reentrant transition is also found at lower temperatures. The reentrant transition arises due to competition between polymer-polymer and polymer-water hydrogen bonds. The balance between the two types of hydrogen bonding can be shifted to either direction through changes not only in temperature, but also by pressure, mechanical force, osmotic stress, or other external influences. Both polypeptides and polynucleotides are considered within a unified formalism. Our approach provides an explanation of the experimental difficulty of observing the reentrant transition with pressure and underscores the advantage of pulling experiments for studies of DNA. Results are discussed and compared with those reported in a number of recent publications with which a significant level of agreement is obtained.
authors: Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia, Venezia, Italy. abadasyan@gmail.com
authors: A V
authors: AV
authors: Badasyan
authors: Sh A
authors: ShA
authors: Tonoyan
authors: Y Sh
authors: YSh
authors: Mamasakhlisov
authors: Achille
authors: A
authors: Giacometti
authors: A S
authors: AS
authors: Benight
authors: V F
authors: VF
authors: Morozov
mesh_terms: D001696:Biomechanical Phenomena; D001704:Biopolymers / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D014867:Water / Q000737:chemistry
chemical_list: D001704:Biopolymers; D009711:Nucleotides; D010455:Peptides; D014867:Water; D004247:DNA