Simple suppression of spurious peaks in TROSY experiments

In H-1-N-15 TROSY experiments of proteins and nucleic acids, where the seco nd coherence transfer delay time tau' has been fixed as 5.6 ms, 1/(2(1)J(NH )), in order to achieve complete spin-state selection, spurious negative pe aks are observed along the N-15 axes. These peaks are often annoyingly larg e, especially for nucleic acids. A simple product operator calculation, how ever, indicated that the shortening of the second delay time tau', which is next to the tl period, would efficiently suppress these spurious peaks, wi thout sacrificing the sensitivities of the TROSY peaks too much. We have sh own for three systems, two 11- and 17-kDa proteins and one 8-kDa DNA duplex , that these spurious peaks can be effectively suppressed with delay times of 3.3 ms for the two proteins and 2.3 ms for the DNA. These delay times, o ptimized by trial and error, for the spurious peak suppression did not depe nd on the magnetic field strength and the temperature very much. Although t he shortened tau' delay times attenuate the TROSY peak intensities by about 10 and 20% for the two proteins and the DNA, respectively, this simple mod ification will be useful for the quantitative uses of TROSY peaks and will result in cleaner spectra for various TROSY-based multiple resonance experi ments. (C) 2000 Academic Press.