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The helix-coil transition in polypeptides: a microscopic approach. II
S A Hairyan1, E S Mamasakhlisov, V F Morozov
1Department of Molecular Physics, Yerevan State University, Armenia.
Biopolymers
|January 1, 1995
Summary
This study reveals that the cooperativity parameter in polypeptides is nonlocal, depending on amino acid sequences. This nonlocality impacts the temperature-dependent helicity in heteropolypeptides.
Area of Science:
- Biophysics
- Polymer Science
- Theoretical Chemistry
Background:
- Previous models established a framework for analyzing polypeptide behavior.
- Understanding the factors influencing helicity and correlation length is crucial for protein folding studies.
Purpose of the Study:
- To analytically estimate correlation length and helicity near transition points.
- To investigate the nature of the Zimm-Bragg cooperativity parameter (sigma).
- To analyze the impact of hydrogen bond closing topology (delta) on cooperativity.
Main Methods:
- Utilized an earlier constructed theoretical model.
- Performed analytical estimations for correlation length and degree of helicity.
- Derived an analytic expression for cooperativity parameters in heteropolypeptide chains.
Main Results:
- Demonstrated that the Zimm-Bragg cooperativity parameter (sigma) is nonlocal, determined by (delta-1) amino acid residues.
- Obtained an analytic expression for cooperativity parameters in heteropolypeptide chains.
- Numerical calculations confirmed that nonlocality of sigma affects temperature-dependent helicity in random heteropolypeptides.
Conclusions:
- The cooperativity parameter in polypeptide chains exhibits nonlocality.
- This nonlocality plays a significant role in the temperature dependence of helicity, particularly in heteropolypeptides with random primary structures.