FIGURE 3.

Kinetic analysis of the CPK28-CaM interaction by biolayer interferometry. A, wavelength shift curves for CPK28 binding to biotin-CaM6 in the Octet system. Biotin-CaM6 was immobilized on streptavidin sensors and was incubated for 30 min (1800 s) with the indicated concentrations of His₆-CPK28 in the presence of 100 μm CaCl₂. B, determination of a dissociation constant for the CPK28-CaM interaction. R_equilibrium was determined for each concentration of His₆-CPK28 (black squares) and was fitted using a 1:1 binding model (black line) as described under “Experimental Procedures.” The K_d computed from fitted data is shown (±S.E.). Data in A and B are representative of three replicate experiments performed with independently prepared samples of recombinant CPK28.