Helix-coil transition in homopolypeptides under stretching.
We consider the effect of an external applied force on the alpha-helix-coil transition of a single-stranded homopolypeptide chain. An annealed scenario is assumed, where the building amino acid monomers may interconvert between random-coiled and ordered alpha-helical configurations. By exact evaluation of the partition function of the freely jointed chain with helix-coil internal degrees of freedom in the thermodynamic limit, we obtain the result that the stress-strain characteristic has an asymmetrical sigmoid shape with a prominent pseudoplateau. Because of the one-dimensional nature of this system, fluctuations dominate over the mean-field approximation, which incorrectly predicts a second-order phase transition.
Tamashiro
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MN
Materials Research Laboratory, University of California, Santa Barbara, California 93106-5130, USA. mtamash@mrl.ucsb.edu
Pincus
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P
D000596:Amino Acids / Q000737:chemistry; D015233:Models, Statistical; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
D000596:Amino Acids; D010455:Peptides; D011506:Proteins