Fig. 2: High-resolution native top-down MS analysis demonstrates heterogeneity of endogenous heterotrimeric cTn complex.

Native MS spectra of the endogenous cTn complex using ultrahigh-resolution FTICR-MS to achieve isotopic resolution. Most abundant charge state (z = 19+) is isolated. Zoomed-in mass spectra shows the isotopically resolved cTn complex proteoforms detected. Theoretical isotope distributions (red circles) are overlaid on the experimentally obtained mass spectrum to illustrate the high mass accuracy. All individual ion assignments are within 2 ppm of the theoretical mass.