Binding of specific ligand by linearly associating enzyme system.

The binding of specific ligand by linearly associating enzyme system M in equilibrium to M2 in equilibrium to M3 in equilibrium... has been discussed. It is assumed that ligand is bound in the region of the contact of monomers and free monomer retains the subsites for specific ligand binding. The character of the dependences of the amount of bound ligand on enzyme and ligand concentrations and the influence of specific ligand on the distribution between oligomeric enzyme forms have been analysed. The high concentrations of specific ligand provoke the dissociation of enzyme oligomers because of occupation of both subsites in monomeric form. The situation is discussed when a specific ligand is the substrate which is converted to the product in an intact binding site located in the region of the contact of monomers. The inhibitory effect of high substrate concentrations has been interpreted, taking into account the blocking of the association of inactive monomers into active oligomers.