FIGURE 3.

Lack of kinetic cooperativity in CBS-PPases in the presence of 10 μm Ap₄A. The panels show (from top to bottom) the catalytic constant k_cat, the Michaelis constant K_m, and the Hill coefficient h. The dashed lines and corresponding points refer to the early estimated parameter values in the absence of Ap₄A (32); K_m values refer to the average Michaelis constants ($\sqrt{K_{\text{m}1}{K}_{\text{m}2}}$) in this case. The horizontal dotted lines (h = 1) mark the boundary between positive and negative cooperativity. K_m values are measured in terms of the MgPP_i complex. dh, dhPPase; cn, cnPPase; cp, cpPPase.