What effect occurs when binding of a different ligand alters substrate binding to adjacent subunits?

The correct choice pertains to the phenomenon known as the heterotropic effect, which occurs when the binding of one ligand influences the binding characteristics of a substrate to adjacent subunits of a protein, typically an enzyme or receptor. In this context, the ligand that binds can be different from the substrate, leading to a change in the functional properties of the enzyme or receptor complex.

In biochemical systems, the presence of a ligand that binds to one subunit can induce a conformational change that affects how another ligand or substrate binds to a nearby subunit. This inter-relationship helps modulate the activity of multi-subunit proteins and illustrates the complexity of allosteric regulation, where one molecule can enhance or inhibit the function of another by binding to a site different from the active site.

To provide further context, the homotropic effect specifically refers to a situation where the binding of a substrate to one subunit influences the binding of the same substrate to neighboring subunits. The allosteric effect encompasses both homotropic and heterotropic influences but is typically described in a broader sense, encompassing changes induced by ligands that may not alter substrate binding specifically. The cooperative effect generally refers to the increased affinity for substrate binding that occurs as a result of binding events, particularly in an