Table 1:

K_Ds and |Δω_max| determined from 2D HSQC titrations for ¹⁵N labeled PAR3G_FD and PAR3G_EL bound to human Prothrombin and Thrombin (wildtype and mutant). For these NMR titrations, the peptide ligand concentrations were kept constant and the protein concentrations were serially diluted. Estimated K_Ds were calculated using in house scripts written in Python. Experimental data employed in the calculations include the individual protein and peptide concentrations and also the ¹⁵N-NMR chemical shift differences between each set of free and bound conditions. The plasma derived ProT and IIa titration series were carried out at least in triplicate. The studies with recombinant R77aA-IIa were done in duplicate. Error analysis was carried out using a Monte-Carlo approach assuming a 10% error in the serially diluted protein samples. See Materials and Methods for more details.

Peptide	Residue	ProT	|Δωmax| (ppm)	Wild Type PPACK-IIa	|Δωmax| (ppm)	R77aA PPACK-IIa
PAR3GFD	F47	64 ± 8 μM	0.23 ±0.01	40 ± 10 μM	1.98± 0.2	173 ± 85 μM
PAR3GFD	D54	65 ± 12 μΜ	0.39 ±0.03	Too tight to calculate	Insufficient data points	168 ± 88 μM
PAR3GEL	L52	124 ± 27μM	0.37 ±0.04	47 ± 6 μM	1.84± 0.08	salt bridge not involved
PAR3GEL	E48	>200 μM	ΝΑ	Too tight to calculate	Insufficient data points	salt bridge not involved