i like this post (click again to cancel)
i dont like this post (click again to cancel) remove favorite mark from this question (click again to restore mark)

Hi all,

In a folded protein with 13C-delta labeled glutamates, how can one distinguish between chemical shift due to protonation and chemical shift due to conformational changes?


asked Feb 24 '11 at 10:35

RCKC's gravatar image


what are you talking about ? variation of chemical shift of which nucleus ? a variation between which solution state ? - Yoan Monneau (Feb 25 '11 at 06:19)

I'm guessing that it's C13 delta shift, as for the solution states it is less clear... - Evgeny Fadeev (Feb 25 '11 at 11:43)

2 Answers:
i like this answer (click again to cancel)
i dont like this answer (click again to cancel)

It's probably best to look at the structure separately - using the structural restraints derived from the NMR data - NOE', J-couplings, etc. The 13C shift of glutamate C-delta atoms alone won't give the answer.

Maybe it is possible to change the pH, while monitoring NOEs and couplings?

As glutamate becomes protonated, the structural changes may happen as well - so it may be both.


answered Feb 25 '11 at 12:02

Evgeny%20Fadeev's gravatar image

Evgeny Fadeev

updated Feb 25 '11 at 12:05

i like this answer (click again to cancel)
i dont like this answer (click again to cancel)

Are the two changes, the protonation and change in conformation occuring simulatneously or is it question of finding out which one of the two factors is contributing to chemical shifts/variations in the shifts.

In such cases it may be better to ascertain the posssible trends/magnitudes of changes for the two causes etc., by a theoretical calculation of the relevant approximate geometries and try to follow the experimentally observed variations based on the possibilities. The guessed structure or theoretical values may not be reproducing experimental values accuartely but certain inferences can be helpful instead of relyin only the analysis of experimental spectra. look up some of the observations in my posters at crsi-13nsc and nmrs2011 at the following URL: 13nsc and nmrs2011




answered Feb 27 '11 at 22:57

SankarampadiAravamudhan's gravatar image


updated Feb 27 '11 at 22:59

Your answer
Please start posting your answer anonymously - your answer will be saved within the current session and published after you log in or create a new account. Please try to give a good answer, for discussions, please use comments and please do remember to vote (login to vote)
toggle preview

powered by CNPROG