C. Monot et al., REPRESENTATION OF AFFINITY IN THE CASE OF COOPERATIVITY IN PROTEIN-LIGAND BINDING, Fundamental and clinical pharmacology, 8(1), 1994, pp. 18-25
We have already proposed a ''Global Association Function'' to represen
t the global affinity of proteins to a drug; it was first applied in t
he case of independent binding sites. In this paper, we show that this
same function can also be used to assess interactions between sites b
y varying the number of interacting sites and their co-operativity lev
el. The resulting curves in two application cases are given together w
ith the corresponding Scatchard plot: i) in a system with one single c
lass of identical and interacting sites, ii) in a system with two clas
ses of sites in which either primary or secondary are interacting; une
xpectedly, in this latter case we also observed that sometimes positiv
e co-operativity occasionally resulted in a concave-up Scatchard plot
which is unusually admitted. In addition, as described in one example,
our function is assumption free; this might be an advantage over usua
l methods, such as discrete parameter methods, because they require ad
ditional and empirical hypotheses on their related binding model.