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. Author manuscript; available in PMC: 2014 Dec 24.
Published in final edited form as: Anal Chem. 2007 May 12;79(12):4433–4441. doi: 10.1021/ac062309s

Figure 2. Detection of MTs in RWPE cells by MALDI-MS following sample preparation by trypsin digestion and subsequently gel filtration.

Figure 2

Diagram (A) shows the tryptic digest of the “MT crude fraction” prepared from RWPE cells was comprised of a large number of peptide species majority of which were below 4000 Da; (B) MTs in the same sample became readily detectable as 1+, 2+ and 3+ ions after gel filtration where the interfering peptide species were effectively removed; (C) The enlarged spectrum shows the observed masses representing four MT isoforms, 1E, 1G, 1X and 2A, in modified (N-term acetylated) and unmodified forms (see text at page 15 for more details). (D) The isotopes of MT-2A were well resolved (solid line), matching well to the theoretical isotope profile (dash line). The molecular formula of singly charged (protonized) MT-2A is C225H384N71O83S21, and the respective theoretical isotope distribution with a resolution of 10 000 being computed by Data Explorer Version 4.9.