Folding/unfolding kinetics of lattice proteins studied using a simple statistical mechanical model for protein folding, I: Dependence on native structures and amino acid sequences

Haruo Abe, Hiroshi Wako

研究成果: Article査読

9 被引用数 (Scopus)

抄録

The folding/unfolding kinetics of a three-dimensional lattice protein was studied using a simple statistical mechanical model for protein folding that we developed earlier. We calculated a characteristic relaxation rate for the free energy profile starting from a completely unfolded structure (or native structure) that is assumed to be associated with a folding rate (or an unfolding rate). The chevron plot of these rates as a function of the inverse temperature was obtained for four lattice proteins, namely, proteins a 1, a 2, b 1, and b 2, in order to investigate the dependency of the folding and unfolding rates on their native structures and amino acid sequences. Proteins a 1 and a 2 fold to the same native conformation, but their amino acid sequences differ. The same is the case for proteins b 1 and b 2, but their native conformation is different from that of proteins a 1 and a 2. However, the chevron plots of proteins a 1 and a 2 are very similar to each other, and those of proteins b 1 and b 2 differ considerably. Since the contact orders of proteins b 1 and b 2 are identical, the differences in their kinetics should be attributed to the amino acid sequences and consequently to the interactions between the amino acid residues. A detailed analysis revealed that long-range interactions play an important role in causing the difference in the folding rates. The chevron plots for the four proteins exhibit a chevron rollover under both strongly folding and strongly unfolding conditions. The slower relaxation time on the broad and flat free energy surfaces of the unfolding conformations is considered to be the main origin of the chevron rollover, although the free energy surfaces have features that are rather complicated to be described in detail here. Finally, in order to concretely examine the relationship between changes in the free energy profiles and the chevron plots, we illustrate some examples of single amino acid substitutions that increase the folding rate.

本文言語English
ページ(範囲)3442-3454
ページ数13
ジャーナルPhysica A: Statistical Mechanics and its Applications
388
17
DOI
出版ステータスPublished - 2009 9 1

ASJC Scopus subject areas

  • 統計学および確率
  • 凝縮系物理学

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