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Dear All, Unlike most other programs we do not have (the equivalent of) a single resonance for e.g. Lys HE*. I still think ours is the correct description. Systems that are symmetric or in fast exchange, like CH3 or flipping phenylalanine are degenerate, and get one resonance corresponding to several protons. Prochirals are not degenerate, they just happen to have the same shift in one particular spectrum. I'd say that representing them as two resonances with identical shifts describes the situation perfectly. To be sure it does mean that you have to remember to assign all peaks as ambiguous 'HE2 or HE3', or errors will creep in. I preferred HE2/HE3 instead of HEa/HEb because it contains more information. If the shifts really are identical you *do* know for certain the shift of both stereoassigned protons. If you do not like it, you still have the option of assigning ambiguously to HEa/HEb, or to just HEa if you are not sure they are both there. I am more open to argument on this one, though. We also considered another alternative: to remove HE* (etc.) from the program completely. It does not correspond to the underlying information, being just a shorthand for something else, and people tend to get tripped up because it does not behave the way they expect. Any suggestions? Yours, Rasmus --------------------------------------------------------------------------- Dr. Rasmus H. Fogh Email: [log in to unmask] Dept. of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK. FAX (01223)766002 On Tue, 3 Jun 2008, Wayne Boucher wrote: > Hello, > > Tim says: > > Firstly, there is no change of policy. > > There is a new annotation bug which means that He* assignment option gives > "He2/He3", rather than the compressed form "He*" (which still works for > Hea + Heb), but aside from that the assignment still looks OK when I > test. > > We're going to need more information to reproduce this. > > I'm on the side of going for ambiguous giving Hea/Heb to start with, but > Rasmus suggested otherwise. > > For v2 I may add an "Ambiguous is stereo" toggle option. > > Wayne > > On Tue, 3 Jun 2008, Christoph Brockmann wrote: > > > Hi Everyone, > > > > Is it just me, or is there something new in the way how Analysis handles > > degenerate proton shifts. I just assigned He* to a resonance and got > > back an assignment for He2 only... (last I remembered was that you > > should get He2/He3 at least). Besides the fact that I would be cool if > > Analysis could actually remember that I think these shifts are > > degenerate (there is a tendency for the frequencies of He2 and He3 to > > split at later stages of the project), or that it would be far more > > sensible that the assignment would at least go to Hea/Heb (normally you > > don't really know anything about your stereospecifics really), it is > > completely difficult to deal with the specific assignment for He2... > > > > I really hope this is just a bug... > > > > Thanks, > > Christoph > > > > > > -- > > --------------------------------------------------------- > > Dr. Christoph Brockmann > > Division of Structural Studies > > MRC Laboratory of Molecular Biology > > Hills Road > > Cambridge, CB2 2QH > > phone: +44-1223-40-2261 or +44-1223-40-2042 > > e-mail: [log in to unmask] > > --------------------------------------------------------- > > >