ALLOSTERIC FERMENT STRENGTH REGULATION
Allosteric regulation is one of the types of ferment strength regulation. This type of regulation presents the effect, which is observed, when small molecules (effectors), while bonding with a ferment not in the region of the active centre, change the reaction rate. Such regulation can be either homotropous (when a molecule of the substrate in interaction with a ferment changes its affinity to molecules of the same substrate), or heterotropous (when affinity to the substrate changes by interaction of a ferment with a molecule, which is not similar to molecules of the substrate. Both homotropous and heterotropous effectors can be either activators or inhibitors.
Allosteric activator acting on a ferment, if described by the symmetrical model, will preferably bond with R-conformer and stabilize this state. As the result, the activator will increase the initial concentration of R-conformers comparing with the concentration of T-conformers, and, consequently, it will increase the affinity of the ferment to its substrate (positive cooperativity).
Allosteric inhibitor, on the contrary, preferably bonds and stabilizes a ferment in the T-state, causing by means of this decreasing of the affinity of the ferment to its substrate (negative cooperativity).
As a whole, the role of allosteric effectors are in either in extending (in the case with inhibitor) or in narrowing (in the case with activator) the rating of substrate concentration, in which the ferment is capable of increasing of the reaction rate.