MULTVALENCY: STRENGTH IN NUMBERS

Many biological processes are set into motion when two molecules bind to each other. These binding events are often monovalent in nature—such as when a single binding site on a ligand sticks to a single binding site on a receptor. And monovalent interactions are often remarkably effective. But if monovalent interactions are good, wouldn't bivalent, trivalent, or higher valency interactions be better? For some biological processes, nature seems to have answered this question in the affirmative. Indeed, some multiple binding interactions between a multivalent ligand and a multivalent receptor are not only just a little better but, in fact, are orders of magnitude better. Multivalency is the simultaneous attachment of two or more binding sites on one biological molecule or organism (such as a protein or virus) to multiple receptor sites on another (such as a cell surface). Scientists have long known that multivalent interactions play an essential role in biological processes. But they have ...