The Flory isolated-pair hypothesis is not valid for polypeptide chains: Implications for protein folding
AUTOR(ES)
Pappu, Rohit V.
FONTE
The National Academy of Sciences
RESUMO
Using an all-atom representation, we exhaustively enumerate all sterically allowed conformations for short polyalanyl chains. Only intrachain interactions are considered, including one adjustable parameter, a favorable backbone energy (e.g., a peptide hydrogen bond). The counting is used to reevaluate Flory's isolated-pair hypothesis, the simplifying assumption that each φ,ψ pair is sterically independent. This hypothesis is a conceptual linchpin in helix–coil theories and protein folding. Contrary to the hypothesis, we find that systematic local steric effects can extend beyond nearest-chain neighbors and can restrict the size of accessible conformational space significantly. As a result, the entropy price that must be paid to adopt any specific conformation is far less than previously thought.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=18804Documentos Relacionados
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