Figure 11.

The effects of compounds on MgATP binding and the subsequent isomerization step in the actin–S1 complex.A, normalized equilibrium constant K₁ (Fig. 2) for ATP binding to S1 in the rigor PFA.S1 complex (0.05 μM) in the absence (Con) and presence of each compound. B, normalized rate constant k₊₂, for the isomerization to the weak-binding state. Before normalization, the Con values are K₁ = 2.4 ± 0.03 nM⁻¹ and k₊₂ = 1620 ± 80 s⁻¹ (Table 1). The effects for K₁ and k₊₂ are categorized as mild (blue, <1.5-fold), moderate (violet, 2–3-fold), or severe (pink, >3-fold). [Compound] was 100 μM, except Mit was 5-fold and Flu and Dan were 25-fold over [PFA].