1998/04/22 by D. K. Klimov, D. Thirumalai
Physics and Astronomy · Biochemistry, Genetics and Molecular Biology · #cond-mat.soft #q-bio
published as Folding & Design 3, 127-139 (1998) · 29 pages, Latex, 12 ps figures
arxiv created 1998/04/22 · arxiv updated 2009/11/30
We consider equilibrium folding transitions in lattice protein models with and without side chains. A dimensionless measure, Omegac, is introduced to quantitatively assess the degree of cooperativity in lattice models and in real proteins. We show that larger values of Ωc resembling those seen in proteins are obtained in lattice models with side chains (LMSC). The enhanced cooperativity in LMSC is due to the possibility of denser packing of side chains in the interior of the model protein. We also establish that Ωc correlates extremely well with (σ= (Tθ -Tf )/Tθ), where (Tθ) and (Tf) are collapse and folding transition temperatures, respectively. These theoretical ideas are used to analyze folding transitions in various real proteins. The values of Ωc extracted from experiments show a correlation with σ. We conclude that the degree of cooperativity can be expressed in terms of the single parameter σ, which can be estimated from experimental data.