Fibrin(ogen) residues γ390-396 do not accelerate FXIII-A₂ activation. rFXIII-A₂ (10 µg/mL [60 nM], final) was mixed with γA/γA or Fibγ^390-396A fibrinogen (150 µg/mL [440 nM], final). Reactions were triggered by addition of thrombin (2 nM, final) and CaCl₂ (10 mM, final), quenched at the indicated time points, and analyzed by SDS-PAGE with western blotting and densitometry. Activation peptide cleavage was detected using anti-FXIII-A antibody. Fibrin crosslinking was detected using anti-fibrinogen antibody. (A) Representative western blots and (B) quantitation of rFXIII-A₂ activation over time from all blots. (C) Maximal rates of rFXIII-A₂ activation were calculated from quantified western blots. (D) Representative western blots of fibrin crosslinking and quantification of (E) γ-γ dimer formation and (F) formation rate. Data are means ± SEM; N = 4 experiments.