Fig 6. Effect of NSGM 13 on FXIIIa-mediated fibrin crosslinking.

(A) The formation of crosslinked fibrin upon addition of aqueous solution of thrombin (2.5 μg/mL) to aqueous solution of fibrinogen (10 mg/mL) and human FXIIIa (2.0 μg/mL) was measured spectrophotometrically at 405 nm and 25°C. The reaction was carried out in 50 mM TrisHCl buffer of pH 7.4 containing 10 mM CaCl₂ and in the presence or absence of thrombin, FXIIIa, or NSGM 13 (5, 50, and 500 μM). (B) Relative fibrin crosslinking (%) of a solution containing fibrinogen (10 mg/mL), FXIIIa (2.0 μg/mL), thrombin (2.5 μg/mL), and 10 mM CaCl₂ in the presence of various concentrations of NSGM 13 was determined by measuring the absorbance of each well at 405 nm, pH 7.4, and 25°C. Solid lines represent sigmoidal fits to the data to obtain IC₅₀, HS, Y_M, and Y_O using Eq 1. See details in Materials and Methods.