Dear NMRWikiers, I'm fresh in nmr field and would like to ask couple questions: 1. Our protein has about 132 residues.The NHSQC is well dispersed but many peaks can't be found in CBCANH and CBCACONH. HNCA/HNCOCA + HNCO/HNCACO are planned for backbone assignment. Other people processed data with NMRPipe. The NHSQC peaks can mostly find matching peaks in HNCO/HNCACO, while HNCA/HNCOCA can't be matched (no same resonances can be seen when synchronized). But, many peaks can be seen in HNCA/HNCOCA. I found that the whole scale of 13C axis in HNCA is from 51 to 66 and the one in HNCOCA is from 42 to 73. Maybe this is the reason for peak un-matching in these two spectra. Where is the problem in processing? Is it possible to correct by re-processing? 2. I'm using SPARKY to do assignment. In Strip Plot, after "Add selected strip peaks" (HNCO + HNCACO),Pointer Mode in "find/add peak", pick the peak in HNCACO, hold "Shift" down and click HNCO window and selected, go to "Find - Add strips matching peaks", but only HNCACO strips are added, never HNCO. What's wrong?
Many thanks in advance,
asked Jan 25 '12 at 17:48
it seems to be while taking experiments , you kept wrong or mismatched spectral widths in f1, f2 , f3 axis.
usually we use following spectral widths HNCA C13 - 30 ppm N - 40 ppm H - 14.1 PPM HNCOCA C13 - 30 ppm N - 40 ppm H - 14.1 PPM HNCO CO - 20 ppm N - 40 ppm H - 14.1 PPM HNCACO CO - 20 ppm N - 40 ppm H - 14.1 PPM Just cross check with your experiments above spectral widths , if every thing fine , do synchronization (adjust ppm if find any difference still ) by using ST command in sparky .