[Specific ligand induced dimerization of allosteric enzymes].
The kinetic behavior of dissociating enzyme system of the type: inactive monomer reversible active dimer where the dimeric form is stabilized by a specific ligand (in particular by substrate) which is bound in the region of the contact of monomers has been analysed. It is assumed that the dissociation of the dimer results in formation of the monomer, which retains the subsites for specific ligand binding. The shape of the dependences of enzyme reaction rate (v) on substrate concentration (S) is characterized using the order of enzyme reaction rate with respect to substrate concentration: ns = dlnv/dln[S]. When the substrate concentrations are low the dependences of v on [S] have S-shaped form (the maximum value of ns exceeds the unity) at the definite values of parameters of the enzyme system. The value of ns approaches -2 at sufficiently high substrate concentrations (in the region where the substrate reveals the inhibitory effect due to blocking the association of inactive monomers into active dimer). The methods of calculation of the parameters of the dissociating enzyme system under discussion have been elaborated on the basis of the analysis o the experimental dependences of specific enzyme activity on enzyme concentration obtained at various fixed substrate concentrations. It has been shown that depending on its concentration allosteric effector may act as an activator or an inhibitor.
D000494:Allosteric Regulation; D000495:Allosteric Site; D004798:Enzymes / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D046911:Macromolecular Substances; D008433:Mathematics; D008956:Models, Chemical
D004798:Enzymes; D008024:Ligands; D046911:Macromolecular Substances
Indutsiruemaia spetsificheskim ligandom dimerizatsiia allostericheskogo fermenta.