title: Protein structure along the order-disorder continuum.
abstract: Thermal fluctuations cause proteins to adopt an ensemble of conformations wherein the relative stability of the different ensemble members is determined by the topography of the underlying energy landscape. "Folded" proteins have relatively homogeneous ensembles, while "unfolded" proteins have heterogeneous ensembles. Hence, the labels "folded" and "unfolded" represent attempts to provide a qualitative characterization of the extent of structural heterogeneity within the underlying ensemble. In this work, we introduce an information-theoretic order parameter to quantify this conformational heterogeneity. We demonstrate that this order parameter can be estimated in a straightforward manner from an ensemble and is applicable to both unfolded and folded proteins. In addition, a simple formula for approximating the order parameter directly from crystallographic B factors is presented. By applying these metrics to a large sample of proteins, we show that proteins span the full range of the order-disorder axis.
authors.affiliation: Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Charles K
authors.initials: CK
authors.lastname: Fisher
authors.forename: Collin M
authors.initials: CM
authors.lastname: Stultz
mesh_terms: D019295:Computational Biology; D006801:Humans; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D013696:Temperature
chemical_list: D011506:Proteins