Analysis of XEG inhibition by purified NEC4. The experiment was conducted and analyzed as outlined in “Materials and Methods.” Experimental data are represented by black circles, and the theoretical function corresponding to the best fit to these data is represented by a solid curve. Dashed lines (—) are drawn from the point (0,
v0) through the theoretical curve at points
where
n is an integer. The distance (0.45 nm) between successive intercepts of these lines with the [I]
t axis is an estimation of
Ki,app. The competitive inhibition constant
Ki is calculated as follows: