Enzyme Kinetics

Kinetic equations and ligand binding equations may be very similar. The four most widely employed kinetic formats are the Michaelis–Menten, Lineweaver–Burk, Eadie– Hofstee, and Hill. The effective binding range for a ligand with constant affinity is nearly 100-fold. At [L] ≤ 0.1Kd, binding becomes ineffective. At [L] ≥ 10Kd, binding approaches saturation. This effective binding range is easily remembered as the 2-log rule. The effect of positive cooperativity is to make the binding range narrower, so that saturation is approached below [L] = 10Kd, by changing the affinity for the ligand. The effect of negative cooperativity is to extend the binding range so that saturation is never approached under physiological concentrations of the ligand.