FIGURE 4.

Effect of tβ₄ on the distance between bound ɛATP and Lys-61 of actin. Corrected and averaged fluorescence spectra (λ_ex = 315 nm and λ_em = 415 nm) of ɛATP- and ɛATP/FITC-actin in the absence (solid curves) and presence of 10-fold molar excess tβ₄ (dashed curves). The actin concentration was 1.5 μM in G-buffer containing 1 mM Tris/HCl pH 8.0 and 0.1 mM CaCl₂. The temperature was 10°C. Spectra were normalized to a labeling ratio of FITC to actin equal to one.