Organisms operate through chemical reactions, and every reaction has an equilibrium point. Enzymes cause reactions to occur more rapidly, but they do not change the equilibrium. The interactions of enzymes and other proteins with substrates entail weak bonds, so there are equilibria between the proteins associated with their ligands or dissociated from them. These weak interactions allow proteins to do their work. Computers help people compare the amino-acid sequences of newly discovered proteins with those whose functions are known and this provides clues to the functions of the new proteins.