Hi All,
I am trying to work out (or verify) why the correlation peaks for couplings to diastereotopic methylene protons are so weak in some COSY spectra. I am fairly sure that it is just a funtion of the number and size of the passive couplings, but I would like to make sure by modelling a few examples. The expression for the transfer function for the AM coupling in an AMX spin system is given in the classic CT-COSY paper by Rance et al (M. Rance, G. Wagner, O. W. Sørensen, K. Wuthrich, R. R. Ernst, Journal of Magnetic Resonance 1984, 59, 250–261), but only applies for a single (fixed) evolution time. In a non-CT COSY experiment, the evolution time increments with t1 and the coupling pattern may be considerably more complex. For example, one of the examples I am looking at would be the AM coupling in an AMNX3 system, where the AN coupling is also active and A is involved in an additional AY3 coupling. The M-N, M-X3, and N-X3 couplings are all significant and constitue passive couplings.
Just before I set about re-inventing the wheel, I wondered if anyone knew of a paper that dealt with the more general case (I couldn’t find one), or knew of a piece of code that could simulate the transfer function. I know that the Spinach library certainly could, but I am wondering if that is overkill for this problem?
Any suggestions gratefully received.
Thanks,
Alan
Received on Wed Dec 16 2020 - 04:15:06 MST