Analysis of filamin and alpha-actinin binding to actin by the stopped flow method

We ascertained by the stopped flow method the overall association rate constant, k+1, of filamin and alpha-actinin to fluorescently labelled filamentous actin of approximately 1.3 x 10(6) M-1.s-1 and approximately 1.0 x 10(6) M-1.s-1 as well as the overall dissociation rate constant, k-1, of approximately 0.6 s-1 and approximately 0.4 s-1, respectively. The overall equilibrium constant, K, for filamin and alpha-actinin to actin deduced from the relation K = k+1/k-1 agree well with published data.