Table 2.

Transient kinetic parameters measured for the exon 7 chimeric S1 isoforms Values are mean ± S.D. based on a minimum of 3 preparations. K₁k₊₂ is the second order rate constant for ATP-induced dissociation of acto-S1. K_D and K_AD are dissociation equilibrium constants determined by division of the dissociation rate constant by the association rate constant (e.g. K₃ = k₋₃ / k₊₃). k_−D and k_−AD are the ADP dissociation rate constants in the absence and presence of actin, respectively. K_AD / K_D is the thermodynamic coupling constant describing the relationship between actin and ADP affinities ²⁸.

S1 Isoform	IFI†	IFI-7a	EMB†	EMB-7d	EMB- 7a/7d	EMB- 7d/7a
K1k+2 (106 M−1 s−1)	0.75 ± 0.08	0.33 ± 0.07	0.91 ± 0.13	0.64 ± 0.05	0.67 ± 0.18	0.66 ± 0.14
k−D (s−1)	7.5 ± 1.3d	4.7 ± 0.8c,d	1.8 ± 0.4c	4.3 ± 0.7c,d	2.6± 0.04c,d	6.1 ± 0.08d
KD (μM)a	7.5	4.7	1.8	4.3	2.6	6.1
KAD (μM)	409 ± 26d	239 ± 52c,d	587 ± 48c	596 ± 39c	191 ± 59c,d	220 ± 33c,d
k−AD (s−1)b	4090	2390	5870	5960	1910	2200
KAD / KD	55	51	326	139	73	36

^aData are estimated from k_−D assuming an association rate constant of 10⁶ M⁻¹ s⁻¹.

^bData are estimated from K_AD assuming an association rate constant of 10⁷ M⁻¹ s⁻¹.

^†Data are from Miller et al. ¹¹

^cp < 0.05 determined by Student's t-test as compared to IFI

^dp < 0.05 determined by Student's t-test as compared to EMB