(A) Visual comparison of the Km values for FXIII (28–41) V34 (white), V34L (dotted), V34P (gray), and V34F (dark gray) AP in the presence of the thrombin mutants W60dA, Y60aA, W215A, E217A, and WE. (B) Visual comparison of the kcat values for FXIII (28–41) V34 (white), V34L (dotted), V34P (gray), and V34F (dark gray) AP in the presence of the thrombin mutants W60dA, Y60aA, W215A, E217A, and WE. An HPLC assay described in Experimental Procedures was used to obtain data to calculate these individual kinetic parameters. The results shown represent averages from at least three independent experiments.