TABLE 3.
Affinity for fXIa binding to fIX, fIXα, and fIXaβ
Using surface plasmon resonance, fXIa species (1 to 5000 nm) in Ca2+-containing HBS-P buffer were perfused across sensor chips coated with fIX, fIXα, or fIXaβ. HBS-P buffer without fXIa was then perfused for 10 min to follow dissociation. Data were corrected for nonspecific binding by subtracting signals obtained with analytes infused through a flow cell without coupled protein. Binding was analyzed using a bivalent binding model for all species except fXIa-CD/PK-HC and fXIa-CD, which were evaluated with a 1:1 binding model. Kd values were calculated from the quotient of the derived dissociation (kd) and association (ka) rate constants.
| Analyte |
Kd for binding of analyte to ligand |
||
|---|---|---|---|
| Factor IX | Factor IXα | Factor IXaβ | |
| nm | |||
| fXIa-WT | 130 ± 20 | 140 ± 30 | 60 ± 10 |
| fXIa-HC | 90 ± 20 | 70 ± 10 | 70 ± 10 |
| fXIa-CD | >5000 | >5000 | >5000 |
| fXIa/PKA3 | >3000 | >3000 | >3000 |
| fXIa-CD/PK-HC | >5000 | >5000 | >5000 |
| fXIa/PKA2-Ser140 | 40 ± 10 | 40 ± 10 | NDa |
a ND, not done.