Dear Bruker Users:
One of the research groups in our Department is doing more and more work
involving structural characterization of fairly large polysaccharides.
The last one we worked on was ~50 kDa, small for some I realize but
large for me given that most of the work I do involves small organic
molecules. In general, I've had decent success playing with HMBC at 500
MHz to nail-down the linkage positions, using both temperature and the
lr evolution time as variables. However, problem systems are still on
my to-do list.
I am aware of the dipole-dipole cross-correlation experiment of Vincent
and Zwahlen (JACS 2000, 122, 8307) and have been trying to get it
working on our AVANCE 500. The app lab @ Bruker BioSpin Canada
graciously provided a pulse sequence but as of today, I have not had any
success getting the experiment to work. The 1-bond antiphase doublets
are always present but no long range correlations. I have tried
constant-time periods between 10-20 msec.
I would be grateful to those on this list who have had success with this
experiment if they could get back to me with any possible suggestions?
I'd like to get my hands on a data set from somebody so I could
carefully compare all parameters against those that I've been using.
For the record, my platform is xwin 3.5 pl6 Windows. Also, is anybody
out there using any other experiment other than HMBC, NOESY/ROESY, or
this DDCC technique for linkage information?
Thanks so much in advance!
Cheers!
Mike
---------------------------------------------
Michael D. Lumsden, Ph.D.
NMR Facility Manager
Atlantic Region Magnetic Resonance Centre
Room 428, Department of Chemistry, Dalhousie University
Halifax, Nova Scotia, Canada, B3H 4J3
phone:(902)494-1635
FAX: (902)494-1310
email: mike.lumsden@dal.ca
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