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Exploring the relationship between funneled energy landscapes and two‐state protein folding
Author(s) -
Konermann Lars
Publication year - 2006
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.21080
Subject(s) - folding funnel , energy landscape , native state , folding (dsp implementation) , contact order , downhill folding , protein folding , chemical physics , random coil , brownian dynamics , observable , chemistry , crystallography , physics , brownian motion , phi value analysis , thermodynamics , quantum mechanics , circular dichroism , biochemistry , electrical engineering , engineering
It should take an astronomical time span for unfolded protein chains to find their native state based on an unguided conformational random search. The experimental observation that folding is fast can be rationalized by assuming that protein energy landscapes are sloped towards the native state minimum, such that rapid folding can proceed from virtually any point in conformational space. Folding transitions often exhibit two‐state behavior, involving extensively disordered and highly structured conformers as the only two observable kinetic species. This study employs a simple Brownian dynamics model of “protein particles” moving in a spherically symmetrical potential. As expected, the presence of an overall slope towards the native state minimum is an effective means to speed up folding. However, the two‐state nature of the transition is eradicated if a significant energetic bias extends too far into the non‐native conformational space. The breakdown of two‐state cooperativity under these conditions is caused by a continuous conformational drift of the unfolded proteins. Ideal two‐state behavior can only be maintained on surfaces exhibiting large regions that are energetically flat, a result that is supported by other recent data in the literature (Kaya and Chan, Proteins: Struct Funct Genet 2003;52:510–523). Rapid two‐state folding requires energy landscapes exhibiting the following features: (i) A large region in conformational space that is energetically flat, thus allowing for a significant degree of random sampling, such that unfolded proteins can retain a random coil structure; (ii) a trapping area that is strongly sloped towards the native state minimum. Proteins 2006. © 2006 Wiley‐Liss, Inc.