Figure 3

nLC/HR-ESI-MS/MS analysis of McrA from M. acetivorans WWM1 and Mko4551. (a) MS spectrum obtained from wild type McrA containing only the methylated precursor 275V-R285-L296 ([M + 4 H]4+; 553.0391 m/z). (b) MS spectrum obtained from Mko4551 McrA containing only the non-methylated precursor 275V-L296 ([M + 4 H]4+; 549.5353 m/z). (c) MS/MS spectrum of the wild type precursor, R = 5-methylarginine. (d) MS/MS spectrum of the Mko4551 precursor. R285 was not methylated. A complete list of calculated and measured masses for the c and z ions is given in Supplementary Table 2. The green and red bars in panels c and d indicate the presence and intensity of different MS2 fragments.