The structure and molecular mechanism of atp synthase are quite extraordinary. as h+ ions flow from the intermembrane space into the matrix of the mitochondria, the conformation of atp synthase shifts in a ratchet-like mechanism, forcing adp and pi together to form atp. but recall that enzymes lower the activation energy for reactions in both directions. assuming the concentration of other molecules is held constant, what reaction would atp synthase catalyze if the concentration of hydrogen ions in the matrix were higher than that in the intermembrane space? note: h+matrix refers to a hydrogen ion in the matrix, while h+ims refers to a hydrogen ion in the intermembrane space. in addition, these equations depict the products and reactants, but are not intended to reflect the correct stoichiometry (numbers of molecules).