Protein conformational exchange measured by H-1 R-1 rho relaxation dispersion of methyl groups
2013 (English)In: Journal of Biomolecular NMR, ISSN 0925-2738, E-ISSN 1573-5001, Vol. 57, no 1, 47-55 p.Article in journal (Refereed) Published
Activated dynamics plays a central role in protein function, where transitions between distinct conformations often underlie the switching between active and inactive states. The characteristic time scales of these transitions typically fall in the microsecond to millisecond range, which is amenable to investigations by NMR relaxation dispersion experiments. Processes at the faster end of this range are more challenging to study, because higher RF field strengths are required to achieve refocusing of the exchanging magnetization. Here we describe a rotating-frame relaxation dispersion experiment for H-1 spins in methyl (CHD2)-C-13 groups, which improves the characterization of fast exchange processes. The influence of H-1-H-1 rotating-frame nuclear Overhauser effects (ROE) is shown to be negligible, based on a comparison of R (1 rho) relaxation data acquired with tilt angles of 90A degrees and 35A degrees, in which the ROE is maximal and minimal, respectively, and on samples containing different H-1 densities surrounding the monitored methyl groups. The method was applied to ubiquitin and the apo form of calmodulin. We find that ubiquitin does not exhibit any H-1 relaxation dispersion of its methyl groups at 10 or 25 A degrees C. By contrast, calmodulin shows significant conformational exchange of the methionine methyl groups in its C-terminal domain, as previously demonstrated by H-1 and C-13 CPMG experiments. The present R (1 rho) experiment extends the relaxation dispersion profile towards higher refocusing frequencies, which improves the definition of the exchange correlation time, compared to previous results.
Place, publisher, year, edition, pages
Springer Verlag (Germany) , 2013. Vol. 57, no 1, 47-55 p.
Relaxation dispersion, Conformational exchange, Rotating-frame relaxation
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-97653DOI: 10.1007/s10858-013-9764-4ISI: 000323673800006OAI: oai:DiVA.org:liu-97653DiVA: diva2:650002
Funding Agencies|Swedish Research Council|621-2010-4912822-2005-2915621-2012-5136|Goran Gustafsson Foundation for Research in Natural Sciences and Medicine||Knut and Alice Wallenberg Foundation||EMBO long-term fellowship||Forum Scientium Award||Alberta Innovates Health Solutions||2013-09-192013-09-192013-09-19