MALDI-TOF for quantification of related proteins

[Minsoo Yoon]

Hello everyone,

I'm interested in quantifying the relative amount of very closely related
preteins (only 2 aa different out of 126 total) using MALDI-TOF.  They have
the same PI and also the same molecular wight, and 2D gels couldn't resolve
them.
When peptide mass was done with trypsin in silico, there are some slight
differences between fragments.  Out of 11 fragments, one protein has 2015,
and 1954 while the other has 2029, and 1940 (Mw).  Would this differences be
sufficient to measure their relative amounts?

Thanks in advance
Minsoo