Figure 5.

In vitro BS3 cross-linking of WT cTn followed by bottom-up MS analysis. A, Coomassie-stained denaturing gradient gel of uncross-linked (−XL) and cross-linked (+XL) products. B, observed precursor MS of the cross-linked peptides between cTnT–Lys-282 and TnC–Lys-6. Observed precursor ion of [M + 3H]³⁺ has m/z 518.2721 with −1.32 ppm mass error. Peptide AKVTGR corresponds to cTnT 281–286. Peptide MDDIYK corresponds to cTnC 1–6. The 4.0272-Da mass shift between the two isotopic clusters indicates the presence of BS3-d₀/d₄. The red text denotes the cross-linked Lys residues.