Table 2.
Dissociation constants koff and t1/2 for [125I]-IL-8 binding in CHO membranes expressing human CXCR2 receptor in the presence of IL-8, GTP and SB265610
|
Dissociation constant (koff) (min−1) |
Half-life (t1/2) (min) |
n | |||
|---|---|---|---|---|---|
| k1 | k2 | (t1/2)1 | (t1/2)2 | ||
| IL-8 | 0.167 ± 0.022 | – | 4.672 ± 0.687 | – | 7 |
| IL-8 + SB265610 | 0.150 ± 0.019 | – | 4.793 ± 0.635 | – | 3 |
| IL-8 + GTPa | 0.165 ± 0.027 | 3.428 ± 1.088 | 4.581 ± 0.796 | 0.251 ± 0.053 | 4 |
| SB265610 | 0.148 ± 0.016 | – | 4.779 ± 0.490 | – | 3 |
| GTPb | 1.129 ± 0.411 | – | 0.791 ± 0.257 | – | 3 |
Data are mean ± s.e.mean for the indicated number of experiments.
a
Indicates that two-phase exponential decay was the preferred fit when compared with one phase, with a P-value of <0.0001 for three experiments and 0.0002 for the fourth experiment.
b
Indicates that the dissociation curve did not reach zero, instead GTP alone could only cause the dissociation of 45.22 ± 5.66% [125I]-IL-8.
CHO, chinese hamster ovary; CXCR, C-X-C chemokine receptor; IL-8, interleukin-8.