FIGURE 2.

Time course of Ca²⁺ dissociation from IAANS-labeled HCM-cTnC mutants incorporated into cTn or TFs. A, Ca²⁺ dissociation traces from WT and HCM-cTnCs incorporated into cTn complexes are shown. The increase in IAANS fluorescence is from cTnC double-labeled (C35^IAANS and C84^IAANS). B, shown are Ca²⁺ dissociation traces from WT and HCM-cTnCs incorporated into TFs, monitored by a decrease in IAANS fluorescence from mono-cysteine cTnC (C84^IAANS). In A and B, proteins equilibrated in pCa ∼ 5.59 were mixed with EGTA buffer to obtain pCa ∼ 7.48. The signals are an average of 7–10 experimental runs, and the solid line shows the fit to a single exponential equation. The experimental conditions are described in detail under “Experimental Procedures.” The signals are offset along the ordinate for easier viewing. The means ± S.E. are shown in Table 1 (n = 3–5).