Study on the quality of recombinant proteins using matrix-assisted laser desorption ionization time of flight mass spectrometry

Table 1 Mrs of non-glycoproteins measured by MALDI-TOF MS

Protein	Number of amino acids	Theoretical Mr	Measured Mr	Relative error (%)
IL-2	134a	15478	15610	2.8
GM-CSF	127	14477	15451	5.56
TNF-α	158a	17484	17517	0.18
nNOS	199a	22248	22306	0.26
IFN-α2b	166a	19378	19533	0.79
CaM fragment	95	10846	10851	0.05

^aAn additional methionine at the NH-2-terminal.