I have some digested protein spots those have already identified with MALDI and I kept them in -20°C for some months.I am facing a problem with quality of spectra to confirm my data with MSMS measurement, when I perform even MS measurement again the quality of spectra is not so good and they are formed only between 500-1000 m/z ratio. It should be noted that I resuspended my sample with solvent (80%TFA and 20%ACN). I am not sure but it seems that after resuspension I lost the good quality spectra. Could you please give me your opinion and your feedback?
Thanks a lot in advance
Agheli
TFA will give ion suppression.
You may overcome this problem by postcolumn (co-) infusion with a mixture of weak organic acids. This is the so called TFA-fix.
How do you perform your MSMS measurement, which technic do you use? If you do this with ESI then you would not see much because the enormoous amount of TFA would suppress the signal.
Hi Roseboom,
I used MALDI TOF/TOF and performed manual MSMS measurement.
After digestion of gel spots, the clock ticks and peptides are lost to walls, oxidize or hydrolyse.
You can keep spots in the gels for longer time but not post digest.
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