✍ Scribed by Audun Bakk; Johan S. Høye
No coin nor oath required. For personal study only.
We study protein folding by introducing a simpliÿed one-dimensional analogy of a protein consisting of N contacts. Closed contacts are assigned a binding energy while open contacts represent several conÿgurations of equal (zero) energy. Furthermore, two neighboring contacts in di erent states are assigned an unfavorable energy. We show that the statistical mechanics of this problem becomes that of the one-dimensional Ising model of N spins. This model generalizes the "zipper" model that has been studied earlier by the authors and co-workers. The distinct new feature of the present model is the possibility to have folding/unfolding simultaneously at several places along the protein. This is a likely feature, in particular for long proteins, and in uences especially the sharpness of the folding/unfolding transition. This sharpness is expressed in terms of a van't Ho enthalpy relation which we study here. By replacing the total length of the protein by an e ective one, results can be directly related to and are similar to those of the "zipper" model. Upon introduction of water interactions both cold and warm destabilization of the protein are exhibited, which also is similar to the results of the "zipper" model.
📜 SIMILAR VOLUMES
The one-dimensional Ising model with a transverse field is solved exactly by transforming the set of Pauli operators to a new set of Fermi operators. The elementary excitations, the ground-state energy and the free energy are found. The instantaneous correlation function between any two spins is cal
The relaxation to equilibrium of a spin chain in a random magnetic field H is investigated; periodic, patchwise and purely random distributions are studied. To close the set of kinetic equations, the Bragg-Williams approximation (BWA) and a triplet closure approximation (TCA) are applied, and stati