Each Michaelis function that expresses the concentration of one of the species AL2, AL and A in terms of the concentration of free ligand (or its logarithm) is the product of two functions each of which represents the degree of ligation or de-ligation of a single site. These hypothetical sites have pK values of pK (SEE ARTICLE) where pK and α are defined by writing the two molecular pK values as pK +/- log2α. The factors are thus real if α larger than or equal to 1, i.e. if the binding of L by A is not positively co-operative. The dependence of [AL] on 1n[L] is compared with relations that represent other ligand-dependent equilibria.
