Need help in CPMG

[phexorbb]

I tried to combine the exchange enhanced sensitivity pulse sequence (Wang CY, Grey MJ, Palmer AG. 2001. Journal of Biomolecular Nmr 21: 361-6) with the TROSY detection scheme (Loria JP, Rance M, Palmer AG. 1999. Journal of Biomolecular Nmr 15: 151-5) by implementing Wang's sequences up to the end point of transverse relaxation(without time labeling) followed by Loria's detection sequence. The 15N 180 degree pulse width was limited to 160us by probe.

Applying the relaxation compensated sequence to a 19kD protein results in oscillating(with respect to Echo delay) R2 around 5Hz, while the self compensated one and the double Hahn-echo one gives 16~25Hz R2, for all well resolved residues.

Longitudinal relaxation rates is around 1Hz, so it is not quite right to have 5Hz R2 in the relaxation compensated experiment. I appreciate very much any suggest on the problem.