The activated CM4 chip was coated with 20 μg/ml IX-bp, by injecting 60 μl of the solution at a flow rate of 10 μl/min, and was blocked with 1 M ethanolamine hydrochloride at a similar flow rate for 7 min. Then 40 μl aliquots (100 nM final concentration) of factors were injected at a flow rate of 20 μl/min for 2 min. Appropriate concentrations of calcium or magnesium ions were added to the buffer (10 mM Hepes, pH 7.4, and 150 mM NaCl). FIX, Factor IX.