ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In this paper we present a statistical mechanics analysis of the helix–coil transition induced by pH change in homopolypeptide. We propose a one-dimensional model where the contribution from each site to the grand partition function includes contribution of ionic origin (due to the repulsive interaction between similarly charged groups) and contribution of nonionic origin (due to the break of intramolecular hydrogen bond, characteristic of the α helix). Through an accurate solution of the model, we derive analytical expressions for a fraction of internal hydrogen bond θ, dissociation degree of the homopolypeptide α, the melting temperature Tm, change of free energy, ΔG, etc. Then we compare the theoretical curve of titration processes with experimental data and we obtain a very good agreement. We note that the model does not have fitting parameters.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.450737
