Table 3.

Summary of equilibrium and pre-steady-state binding data for hAgo2/G–guide RNA complex formation. Numbers in the first row represent equilibrium measurements (K_{d_meas}). Numbers in the second column were calculated from the corresponding association and dissociation rate constants (K_{d_cal} = k_off/k_on = (k₋₁/k₁) × (k₋₂/k₂) × (k₋₃/k₃)). Differences in K_d values for binary complexes determined via equilibrium and pre-steady-state measurements most probably arise from a slight protein aggregation causing a reduced diffusion rate by 2–3-fold leading to an underestimating of k_{+1_bin} and thus higher K_d values. The numbers given are an average of at least two independent experiments. Most experiments were repeated up to three or four times. Standard deviations are given in brackets. * Data taken from [38]. Details are given in the text.

Substrate	Kd_meas (nM)	Kd_cal (nM)	k1 (M−1·s−1)	k−1 (s−1)	k2 (s−1)	k−2 (s−1)	k3 (s−1)	k−3 (s−1)
U–guide *	7 ± 0.9	36	0.6 (±0.001) × 108	6.2 ± 0.6	0.26 ± 0.02	0.17 ± 0.02	0.012 ± 5 × 10−4	0.007 ± 1 × 10−4
G–guide	35 ± 0.4	59	0.16 (±0.006) × 108	2 ± 0.6	0.2 ± 0.06	0.54 ± 0.07	0.02 ± 0.01	0.0023 ± 4 × 10−4
OH-G–guide	7 ± 0.5	21	0.27 (±0.005) × 108	2.1 ± 0.08	0.3 ± 0.2	0.6 ± 0.02	0.013 ± 0.002	0.002 ± 7 × 10−4