Table II.

Kinetic parameters for wild type and His variant G-CSF binding to immobilized G-CSFR at pH 5.5 and pH 7.4

G-CSF Variant	pH 5.5, kon (×10−5 M−1 s−1)	pH 5.5, koff (×105 s−1)	pH 7.4, kon (×10−5 M−1 s−1)	pH 7.4, koff (×105 s−1)
Wild Type	3.6	7.2	4.9	8.3
D110H	2.3	120	3.7a	16a
D113H	2.8	94	2.8	14
Clone 757	1.9	180	3.3	17
Clone Q	0.37	210	0.87a	56a

Values were calculated using a global data fit to measurements made at 25 and 50 nM and 100 and 200 nM at pH 5.5. Uncertainties in model fit values were <5% in all cases.

^aData fit for 50 nM injection only.