Table 1.

SPR measurements of IFN-β and mutants binding to IFNAR1 and the mutant receptors as indicated

Association (k_a), dissociation (k_d), and affinity (K_D) are indicated. Data are represented as the mean ± S.D. of at least triplicate independent experiments. Significance of comparisons calculated relative to the K_D of the IFNAR1-IFN-β interaction. NS, not significant.

Receptor	IFN	ka (mean)	kd (mean)	KD (mean ± S.D.)	-Fold increase (KD) compared to IFNβ	Significance (KD) from IFNβ
		1/ms	1/s	nm
IFNAR1-ECD	IFN-β	1.55 × 105	3.77 × 10−4	3.34 (± 2.23)	1
IFNAR1-ECDY240A	IFN-β	4.66 × 105	1.16 × 10−2	29.1 (± 15.5)	8.71	NS
IFNAR1-ECDY274A	IFN-β	5.39 × 104	8.58 × 10−4	20.6 (± 12)	6.17	NS
IFNAR1-ECDYYAA	IFN-β	4.07 × 105	9.79 × 10−2	232 (± 67.2)	69.46	a
IFNAR1-ECD	IFN-β F63A/L64A	7.40 × 105	7.85 × 10−3	16.8 (± 5.65)	3.00	NS
IFNAR1-ECD	IFN-β E77A/T78A	8.87 × 104	8.51 × 10−4	12.1 (± 5.8)	3.62	NS
IFNAR1-ECD	IFN-β V81A/R82A	5.27 × 105	1.76 × 10−3	7.44 (± 3.72)	2.22	NS
IFNAR1-ECD	IFN-β FLETVR	9.86 × 104	4.65 × 10−2	552 (± 175)	165.27	a

^a p < 0.0001 (one-way ANOVA with Dunnett's multiple comparisons testing).