Fluorescence versus time of AC-Hsp27 plus F-actin. Fluorescence at 485 nm of 1 M AC-Hsp27 versus time after addition of 40 M F-actin in F-buffer at 37°C. The saturated fluorescence value of 432 ± 6 fluorescence units was obtained from an unweighted, nonlinear least squares double exponential fit of the data points and the root mean square deviation of the points from the fit.