Figure 2.

Binding of Ca²⁺and Mg²⁺to apo-state and preincubated N-cTnC.Left panel, the affinity of site II for Mg²⁺ is compared in the apo-state and with Ca²⁺ preincubation in human N-cTnC. Right panel, the affinity of site II for Ca²⁺ is compared in the apo-state and with Mg²⁺ preincubation in N-cTnC. Statistical differences were assessed through ANOVA followed by Tukey's post hoc test. Ca²⁺ titrations were not significantly different. Titration of Mg²⁺ into N-cTnC preincubated with 1 and 3 mM Ca²⁺ was statistically indifferent, but both significantly differed from the apo-state titration (p < 0.0001). N-cTnC, cardiac troponin C with N domain.