Sorry to bother you all again with the hncacb/cbca(co)nh experiments and possible cross-posting,
I met a strange problem with HNCACB/HN(CO)CACB experiments on 50% deuterated sample. I was using Bruker's standard pulse programs hncacbgp2h3d/hncocacbgp2h3d on a sample purified from U-15NH4Cl, 100% D2O, 13C,1H-glucose M9 culture.
Despite the phasing problem I posted on nmrpipe group
http://groups.yahoo.com/group/nmrpipe/message/568
which I didn't get satifactory answer yet, I met another really weird problem with the spectra themselves:
Not all peaks in HN(CO)CACB experiments in positive and CB/CA peaks are not opposite in signs in HNCACB experiments!!!
The chemical shifts are all correct because I finished full backbone assignment on these weird data manually. A strip plot can be viewed at:
http://mbalster.cwru.edu/questions/strips.jpg
HN(CO)CACB and HNCACB spectra are aligned parallell in pair.
What I used are the standard pulse programs and parameter set of Bruker XwinNMR3.5 except I used only 4 instead of 8 scans so actally I didn't finish the full phase cycling.
I wonder whether it's my labeling strategy or that I didn't use full phase cycling that caused such strange problem.
Yufeng
Yufeng Tong
Dept. Physiol. & Biophys.
Case Western Reserve Univ.
Cleveland, Ohio 44106
Tel: (216)368-8654 (O)
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Life is an everlasting game of Weiqi(igo, baduk).
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