The Quest for Simplicity: Remarks on the Free-Approach Models

Łukasz Jaremko*, Mariusz Jaremko, Micha Nowakowski, Andrzej Ejchart

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


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 15N and 13C 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 15N relaxation data for proteins can be satisfactorily interpreted solely with MFA.

Original languageEnglish (US)
Pages (from-to)11978-11987
Number of pages10
JournalJournal of Physical Chemistry B
Issue number36
StatePublished - Sep 10 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


Dive into the research topics of 'The Quest for Simplicity: Remarks on the Free-Approach Models'. Together they form a unique fingerprint.

Cite this