 By using the selective permeability of a pig's bladder, water could be removed from a condensation reaction to shift the equilibrium position of the reaction towards the condensation products according to the principle of Le Châtelier.As enzymes are macromolecules and often differ greatly in size from reactants, they can be separated by size exclusion membrane filtration with ultra- or nanofiltration artificial membranes.This is used on industrial scale for the production of enantiopure amino acids by kinetic racemic resolution of chemically derived racemic amino acids.