15N T1ro Relaxation Data 
Nuclear magnetic relaxation in the rotating frame constitutes a unique source of information on chemical and conformational exchange processes in the microsecond-to-millisecond time scale Thus, alternatively to the classical T2 relaxation data measurement equivalent rotating-frame relaxation rate (T1(ro)) can be measured by applying off- or -on-resonance CW. Such measurements are performed as a function of the spin-lock field strength in 2D HSQC-like experiments ( 96JACS911 , 96BIO9335 , 97JMR509-124 , 97JB363 , 98JMR351-131 , 98JB307 , 98BIO12320 , 99JB213 , 01METH204 ), 04JB195-30 ). Data can be corrected for offset effects using the measured T1 values. Experimental: Usually about 10 spectra with relaxation delays ranging from 0.01 to 0.5 seconds are carried out using 15N spin lock power of 0.5-1 kHz. Peaks heights or integrated peaks can be used to determine the corresponding relaxation rates as a function of spectral dispersion.

1H T1ro values can be also extracted from a 2D 1H-15N correlation map as described in 97JMR509-124 .

Other NMR Experiments:

  • Measurements from a 3D HNCO-TROSY experiment to avoid accidental resonance overlapping 04JB347-30 .

    • Applications:

  • Determination of ultrafast protein folding ( 00JACS5387 ) taking advantage of the chemical exchange effects between folded and unfolded states.
  • R1ro relaxation outside of the fast-exchange limit ( 02JMR157-154 and 03JB39-26 )

    • Mean T1ro (or R1ro) values of some proteins at different fields:

  • R1ro of 12.4 s-1 at 750 MHz (9.7 s-1 at 500 MHz) for alpha-sarcin (150 residues) ( 02JB301-24)
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