The alpha-1,4 linkages of extracellular maltose are hydrolyzed to yield glucose in a reaction catalyzed by maltase-glucoamylase (Nichols et al. 1998; Semenza et al. 2001). In the body, this enzyme is found as a dimer on the external face of enterocytes in microvilli of the small intestine (Hauri et al. 1985), and acts on maltose derived directly from the diet and from the hydrolysis of starch.