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. Author manuscript; available in PMC: 2012 Aug 1.
Published in final edited form as: Anal Biochem. 2011 Mar 29;415(1):52–58. doi: 10.1016/j.ab.2011.03.029

Figure 2. Mass spectra of G93A SOD1.

Figure 2

A. The Ziptipm/z spectrum of 1 μM G93A SOD1 in 10 mM ammonium acetate, showing the charge state distribution of the protein, with the 10th-12th charge states being the most prominent. B. Mathematical deconvolution of the m/z spectrum yields the parent mass spectrum, showing a singular peak centered at a mass of 15941. *The spectrum also contained a small peak centered at 16039 (observable in A as well). This peak, which is 98 mass units larger than Cu,Zn G93A SOD1, likely corresponds to a sulfate (H2SO4) adductremaining from the purification process.C. Overlay of the experimental mass spectrum with the theoretical high resolution mass spectrum calculated from the empirical formula for G93A SOD1 with the program iMass. The high resolution theoretical spectrum is used to illustrate the effects of isotopic broadening, primarily due tothe natural isotope distribution.