Allosteric enzyme with C = Catalytic or active site
A = Allosteric site.

Allosteric activation – When modulator is bound to allosteric site it changes the confirmation of active site, so that substrate can bind. In enhance the enzyme activity and the effect in called +ve co-operativity.

Allosteric inhibition – When −ve modular is bound to allosteric site it changes the active site so that substrate is not bound. If inhibit the enzyme activity and the effect is called −ve co-operativity.

Figure 6.27 Action of Allosteric Enzymes