title: The Quest for Simplicity: Remarks on the Free-Approach Models.
abstract: Nuclear magnetic relaxation provides a powerful method giving insight into molecular motions at atomic resolution on a broad time scale. Dynamics of biological macromolecules has been widely exploited by measuring (15)N and (13)C relaxation data. Interpretation of these data relies almost exclusively on the use of the model-free approach (MFA) and its extended version (EMFA) which requires no particular physical model of motion and a small number of parameters. It is shown that EMFA is often unable to cope with three different time scales and fails to describe slow internal motions properly. In contrast to EMFA, genuine MFA with two time scales can reproduce internal motions slower than the overall tumbling. It is also shown that MFA and simplified EMFA are equivalent with respect to the values of the N-H bond length and chemical shift anisotropy. Therefore, the vast majority of (15)N relaxation data for proteins can be satisfactorily interpreted solely with MFA.
authors: Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37077 Göttingen, Germany.|Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) , Am Fassberg 11, 37077 Göttingen, Germany.
authors: Łukasz
authors: Ł
authors: Jaremko
authors: Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37077 Göttingen, Germany.
authors: Mariusz
authors: M
authors: Jaremko
authors: Centre of New Technologies, University of Warsaw , Banacha 2C, 02-097 Warsaw, Poland.
authors: Michał
authors: M
authors: Nowakowski
authors: Institute of Biochemistry and Biophysics, Polish Academy of Sciences , Pawinskiego 5A, 02-106 Warsaw, Poland.
authors: Andrzej
authors: A
authors: Ejchart
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008962:Models, Theoretical; D011506:Proteins / Q000737:chemistry*; D013223:Statistics as Topic
chemical_list: D011506:Proteins