SDS-PAGE analysis of factor XIIIa–catalyzed cross-linking of fibrin. SDS-PAGE analysis of γ-dimer and α-polymer formation upon thrombin treatment in the presence of factor XIII and calcium in heterozygous Seoul II fibrinogen (right) and normal control. Incubation with thrombin for 0, 1, 2, 5, 10, and 30 minutes formed clots, respectively. More Aα-chain bands remain for the heterozygous Seoul II fibrin clot (arrow) after 30 minutes of reaction time compared to the normal control, suggesting that Aα-chain cross-linking is impaired by Seoul II mutation. Standard (Std) size equals 250, 150, 100, 75, 50, 37, 25, 15, and 10 kDa from top to bottom, respectively.