α-helix↔random coil phase transition: analysis of ab initio theory predictions
Frankfurt Institute for Advanced Studies, Ruth-Moufang Str. 1, 60438 Frankfurt am Main, Germany
Corresponding author: a firstname.lastname@example.org
Revised: 8 October 2007
Published online: 5 December 2007
In the present paper we present results of calculations obtained with the use of the theoretical method described in our preceding paper [Eur. Phys. J. D, DOI: 10.1140/epjd/e2007-00328-9] and perform detail analysis of α-helix↔random coil transition in alanine polypeptides of different length. We have calculated the potential energy surfaces of polypeptides with respect to their twisting degrees of freedom and construct a parameter–free partition function of the polypeptide using the suggested method [Eur. Phys. J. D, DOI: 10.1140/epjd/e2007-00328-9]. From the build up partition function we derive various thermodynamical characteristics for alanine polypeptides of different length as a function of temperature. Thus, we analyze the temperature dependence of the heat capacity, latent heat and helicity for alanine polypeptides consisting of 21, 30, 40, 50 and 100 amino acids. Alternatively, we have obtained same thermodynamical characteristics from the use of molecular dynamics simulations and compared them with the results of the new statistical mechanics approach. The comparison proves the validity of the statistical mechanic approach and establishes its accuracy.
PACS: 82.60.Fa – Heat capacities and heats of phase transitions / 87.15.He – Dynamics and conformational changes / 64.70.Nd – Structural transitions in nanoscale materials / 64.60.-i – General studies of phase transitions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007