2q4z

From Proteopedia

Revision as of 16:21, 20 March 2008

Ensemble refinement of the protein crystal structure of an aspartoacylase from Rattus norvegicus

Overview

X-ray crystallography typically uses a single set of coordinates and B factors to describe macromolecular conformations. Refinement of multiple copies of the entire structure has been previously used in specific cases as an alternative means of representing structural flexibility. Here, we systematically validate this method by using simulated diffraction data, and we find that ensemble refinement produces better representations of the distributions of atomic positions in the simulated structures than single-conformer refinements. Comparison of principal components calculated from the refined ensembles and simulations shows that concerted motions are captured locally, but that correlations dissipate over long distances. Ensemble refinement is also used on 50 experimental structures of varying resolution and leads to decreases in R(free) values, implying that improvements in the representation of flexibility observed for the simulated structures may apply to real structures. These gains are essentially independent of resolution or data-to-parameter ratio, suggesting that even structures at moderate resolution can benefit from ensemble refinement.

About this Structure

2Q4Z is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.

Reference

Ensemble refinement of protein crystal structures: validation and application., Levin EJ, Kondrashov DA, Wesenberg GE, Phillips GN Jr, Structure. 2007 Sep;15(9):1040-52. PMID:17850744

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