Answer:
d. depends on changes in their quaternary structure on binding of substrates or inhibitors
Step-by-step explanation:
Allosteric enzymes are oligomeric proteins composed of subunits or polypeptidic chains. They have a quaternary structure -many subunits and active sites- and express two states, R and T. Both states establish an equilibrium, with or without a joint ligand.
When the transition from one state to the other occurs, symmetry is conserved, but the affinity of a site to a ligand is altered. When a substrate joins one of the sites, it affects other binding sites.
Allosteric enzymes can change their conformation, exhibiting active and inactive conformations as a result of substrate binding at the activated center and regulatory molecules at other binding sites -allosteric centers-.