FIG 4.
Interaction of GbpC with 1,000-, 5,000-, 9,400-, 38,800-, and 70,800-Da dextran was determined using an Auto ITC 200. GbpC adheres to dextran with micromolar affinity. The stoichiometry reported here is the ratio of GbpC to dextran binding. The shaded portions of the table are values for model fits in the reverse mode in Origin, which displays the various parameters calculated for the reversed binding. In preliminary reversed ITC experiments with dextran in the cell and GbpC in the syringe, we observed very similar values (see Fig. S4 in the supplemental material). In similar experiments with AgI/II and SspB, dextran did not show any specific interaction (Fig. S4). Kd, dissociation constant; N, stoichiometry.