FIG. 4.

Fluorescence of TNP-GTP in the absence and presence of GTP. The protein was present at a concentration of 2.5 μM. The increase in the fluorescence intensity of TNP-GTP with respect to that in the protein-free solution is plotted over the TNP-GTP concentration. The fluorescence intensity was recorded at 25°C at a wavelength of 555 nm, and the excitation wavelength was 408 nm.