A composition having an agent adapted to affect a multimeric protein by binding to a binding site of the multimeric protein and thereby affecting an equilibrium of units, wherein the multimeric protein has an assembly having a plurality of said units, wherein each of the units has a first complementary surface and a second complementary surface and wherein the first complementary surface of one unit is associated with the second complementary surface of another unit, provided that the assembly is at least one of different quaternary isoforms on a condition that in the multimeric protein (1) a structure of each of the units determines a structure of the different quaternary isoforms, (2) the units are in the equilibrium and (3) the structure of the different quaternary isoforms influences a function of the multimeric protein.