In metaolomics
1. Regarding manual peak fitting of metabolites - We use chenomx library and HMDB database to know the chemical shift of particular metabolites and match the ppm value in chenomx profiler. Do we need to correlate the chemical shift with metabolite structure (particularly, orientation and environment of responsible H atom) each time?
2. During fitting, I have observed that, in many cases, in a certain range of ppm there are several similar looking peaks (most in singlet and doublet). Usually, the peaks of metabolite can show some shift in ppm value from documented chemical shift (as in database all the spectra are taken in homogeneous condition whereas here we are working with whole cell metabolites- a heterogeneous mixture). I am confused how to determine the exact peak of one metabolite.
3. Next comes, quantification.
We do quantification in area based manner but how to determine the extent of area to allot to individual metabolites? As in the most cases, more than one metabolite gives peak at a certain chemical shift.
For example, at the lactate peak around 1.3 ppm there are other metabolites like threonine, Biotin, caprate etc. giving peaks. How to understand exact contribution of target metabolite under a certain peak area?
Mr. Kar, Looking at the profile most probably there should be used Lorentzian function.
Thank you for your response Ms. Ivanova. But can you explain more? I am in very initial phase of this type of work and looking for more detail information.
[As for note, I am an Indian girl. So. it would be Ms. Kar ( I understand as I haven't uploaded any pic of mine its a confusion) :-))]
Please help me!!!!!