Figure 4.

Guanine nucleotide binding to ^NRel_Seq. A, mant-GTP upon binding to ^NRel_Seq results in increased fluorescence emission. In the presence of different concentrations (5–40 μm) of GTP (left panel) and dGTP (right panel), the fluorescence emission was monitored. The color codes of the curves are as indicated outside the inset. B, the heat change profile of GTP, dGTP, and ddGTP when titrated against ^NRel_Seq using isothermal titration calorimetry. Binding constants were determined by using single-site binding isotherm. The upper panels represent the raw ITC data. The lower panels are the integrated peaks of heat change derived after subtracting the dilution enthalpies for respective nucleotides from the raw data.