FIGURE 3.

TagF catalyzes a sequential Bi Bi mechanism. Initial velocity data are presented in double reciprocal plots of 1/velocity versus 1/[substrate]. A, CDP-glycerol was varied from 100 to 1600 μm while the Lipid ϕ analog was held constant at 0.5 (▼), 1 (○), 2 (●), 4 (□), and 8 (■) μm. B, the Lipid ϕ analog was varied from 0.5 to 8 μm while CDP-glycerol was held constant at 100 (▼), 200 (○), 400 (●), 800 (□), and 1600 (■) μm. Experiments were conducted with 2.5 nm TagF, and initial rates were determined by monitoring the conversion of CDP-glycerol to CMP via PIC-HPLC. Initial rate data were fit to all initial velocity expressions in the Enzyme Kinetics Module 1.1 for Sigma Plot 8.0 using a non-linear sum of least squares regression method and were found to be best described by the expression for a sequential random mechanism (Equation 2). Error bars indicate S.E.