mass spectrometry on Factor XIII

Hi to all,

I am working on mass spectrometry on Factor XIII. Is there anybody who has experience about it? My problem is B2 subunit. I can not get a good result from its spectra.

Thanks in advanced.

Hi ghazaleh842000,

Can you pleasebe more specific about your approach? For instance, are you using MALDI or ESI based method? Are the sample analyzed on the whole protein level or have it been digested? How does the calibration/tuning conditions on the instrument?

Cheers.

Thank you because of your reply Pippuri,

I don't have problem with whole protein. my problem is when I digested it by pepsin. I used MALDI .I did the experiment with A2 and A2B2 subunits and the result at least were better than B2. I can not see any line in B2 :O
I use different matrix ACCA, SA, DHB. But there is nothing. I used different material for callibration as well like PEG,PS.

Thank you!

Hi ghazaleh842000,

How long did you perform pepsin digestion? Have you tried to reduce the digestion time for B2?

Hi ghazaleh842000,

How long did you perform pepsin digestion? Have you tried to reduce the digestion time for B2?

Hello Pippuri,

Finally I got result. Now the problem is that what is it? I can see some spectra but how can I find the peptide order of that mass spectrum? by LC-MS?

Thank you!

Hi ghazaleh842000,

You need to collect MS/MS spectra (which contain information of b/y ion series specific for your peptides) for such assignment.

I am not very familiar with MALDI system- for what I understand, since your sample is mixed with matrix prior to TOF-MS/MS analysis, there is no LC involvement. However, if you were using an ESI-based method, yes, you need to perform an LC-MS/MS run in order to collect spectra for peptide assignment.

Good luck.