The binding of αC fragments 1, 3, and 9 to activated rFXIII-A by SPR in the reverse orientation. With the use of a CM5 sensor chip a serial dilution (0.01-10μM) of GST-free α fragment 1(▴), 3 (♦), and 9 (■) was injected for 60 seconds over directly immobilized activated rFXIII-A at a flow rate of 30 μL/min. SPR response units are plotted against the concentration of fragment injected (μM; n = 3). Error bars show ± 1 SD.