Skip to main content
. Author manuscript; available in PMC: 2010 Sep 15.
Published in final edited form as: Anal Chem. 2009 Sep 15;81(18):7611–7617. doi: 10.1021/ac9009935

Figure 3.

Figure 3

Top: Calculated isotopic distributions corresponding to 0, 1, 2, 3, and 4 disulfide bonds for L126C-4MT GM2AP [M+16H]16+. The calculated m/z distribution decreases by (2)(1.007825)/16 = 0.1260 for each additional disulfide linkage. Bottom: Calculated and experimental isotopic distributions for L126C-4MT GM2AP [M+16H]16+. The close fit of the calculated to the experimental distribution confirms that the protein has the correct amino acid sequence, with four disulfide bonds, and a single 4MT label on a cysteine residue. The five highest-magnitude in the isotopic distribution were chosen for comparison to calculated masses (red dots).