RESUMEN
The effect of quenched sequence disorder on the thermodynamics of RNA secondary structure formation is investigated for two- and four-letter alphabet models using the constrained annealing approach, from which the temperature behavior of the free energy, specific heat, and helicity is analytically obtained. For competing base pairing energies, the calculations reveal reentrant melting at low temperatures, in excellent agreement with numerical results. Our results suggest an additional mechanism for the experimental phenomenon of RNA cold denaturation.
Asunto(s)
Modelos Químicos , ARN/química , Conformación de Ácido Nucleico , Desnaturalización de Ácido Nucleico , Relación Estructura-Actividad , Termodinámica , Temperatura de TransiciónRESUMEN
The generalized model of polypeptide chains is extended to describe the helix-coil transition in a system comprised of two chains interacting side-by-side. The Hamiltonian of the model takes into account four possible types of interactions between repeated units of the two chains, i.e., helix-helix, helix-coil, coil-helix, and coil-coil. Analysis reveals when the energy I(hh)+I(cc) of (h-h, c-c) interactions overwhelms the energy I(hc)+I(ch) of mixed (h-c, c-h) interactions, the correlation length rises substantially, resulting in narrowing of the transition interval. In the opposite case, when I(hh)+I(cc)
Asunto(s)
Simulación por Computador
, Péptidos/química
, Conformación Proteica
, Dicroismo Circular
, Matemática
, Modelos Moleculares
, Datos de Secuencia Molecular
, Mutación
, Conformación de Ácido Nucleico
, Péptidos/genética
, Estructura Secundaria de Proteína
, Termodinámica