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Hello, Tim also adds: For the groups that fail try propagating the assignment across the relevant peaks manually. The system looks at assignments to do its grouping before looking at predicted position etc. If things still fail select the peaks that fail, and in the selected peaks table plot the peak position vs experiment. Does it look possible to fit? Also, increasing the Shift Error setting may help - this is mostly for peak positions that don't really change but wobble by a small amount in random directions. And some things simply won't fit, but looking at the peak positions will usually tell you why. And failing everything, send us the project and let us know an example of what is not working that you think ought to work. Wayne On Tue, 23 Feb 2010, Jan-Christoph Westermann wrote: > Lua Shixiong wrote: >> Hi ccpnmr, >> >> I need to analyze the chemical shifts differences for a series of HSQC with >> increasing ligand concentration. >> >> i have followed the instruction on following chemical shifts in the ccpnmr >> tutorials. But an message showed that a fit failed for X number of groups >> at >> reference position X. And indeed, i was not able to get a fitting for all >> the reference peaks i had. >> >> Could someone please guide me on how to execute the analysis? >> >> Many thanks in advance > > Hi, > > please check that you > > a) grouped the peaks first > > b) have the fitting function set to something sensible (A+Bx usually does > well) > > c) picked peaks in all spectra > > d) have set individual shift lists for all spectra > > This is basically the list of errors that I encountered > when Follow Shift Changes did not work for me. > Alternatively you may want to change the shift change tolerance if you > are experiencing large peak shifts. > > Cheers. > > jcw > > -- > Dr Jan-Christoph Westermann | Phone:+61 (0)7 334 62021 > Research Officer | Group David Craik > Institute for Molecular Bioscience > University of Queensland, > Brisbane 4072, Australia >