Chemical exchange process CPMG experiments

Chemical exchange rate is also determined by Rip experiments in the rotating frame coordinate in which magnetization is spin-locked by application of a radio-frequency field with near-resonance or off-resonance. CPMG experiments in proteins will be apphcable to chemical exchange processes of the value feex[Pg.16]

Ti reports on fast dynamics on a timescale of ps-ns, whereas T2 relaxation depends on both fast and slower dynamics (ps-ns and xs-ms). The experimentally measured T2 relaxation times include an exchange contribution that can be measured by a Carr-Purcell-Meiboom-Gill (CPMG) pulse train (25, 26) or an effective spin-lock field (27-29). The combination of T2 and Tip measurements allows determination of the contribution of chemical exchange to the relaxation time. Eurthermore, relaxation dispersion experiments have been developed to measure slow time-scale xs-ms dynamic processes (30-35). 

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