Molecular mapping of rFXIII-A2* chemically cross-linked to Pep1-Cys and Cys-Pep1 synthetic peptides. (A) rFXIII-A2* chemically cross-linked via Lys446 to Pep1-Cys (PDWGTFEEVSGNVSC). The chemically cross-linked lysine at rFXIII-A2* residue 446 is shown (black rectangle) in addition to potential attachment sites involving key FXIII-A2 residues Tyr167, Val169, Arg171, Glu24, Arg158, and Lys156. (B) rFXIII-A2* chemically cross-linked via Lys257 to Cys-Pep1 (CPDWGTFEEVSGNVS). Cys-Pep1 was also found to be chemically cross-linked to Lys446 in addition to Lys113 and Lys257. Chemically cross-linked Lys257 is shown (black rectangle). Potential attachment sites involved in the binding of Cys-Pep1 include Val169, Arg171, Arg158, and Lys156. The salt bridge interaction between Glu396 of the αC and Arg158 of rFXIII-A2* is shown by the red circles. Both Pep1-Cys and Cys-Pep1 were modeled in the same orientation. Molecular modeling was performed using the Maestro Modeling suite from Schrodinger Inc.
