| Abstract
| - A new 15N constant-time relaxation dispersion pulse scheme for the quantification of millisecond time-scaleexchange dynamics in proteins is presented. The experiment differs from previously developed sequences inthat it includes 1H continuous-wave decoupling during the 15N Carr−Purcell−Meiboom−Gill (CPMG) pulsetrain that significantly improves the relaxation properties of 15N magnetization, leading to sensitivity gains inexperiments. Moreover, it is shown that inclusion of an additional 15N 1800 refocusing pulse (phase cycled±x) in the center of the CPMG pulse train, consisting of 15Npulses, provides compensation for pulseimperfections beyond the normal CPMG scheme. Relative to existing relaxation-compensated constant-timerelaxation dispersion pulse schemes, νCPMG values that are only half as large can be employed, offering increasedsensitivity to slow time-scale exchange processes. The robustness of the methodology is illustrated withapplications involving a pair of proteins: an SH3 domain that does not show millisecond time-scale exchangeand an FF domain with significant chemical exchange contributions.
|
