Evidence for participation of mutarotase in sugar transport: Absence of the enzyme in a case of glucose galactose malabsorption

Abstract

Summary It has been proposed that mutarotase is involved in transport of glucose and galactose. It is the only known substance in intestinal mucosa having a specificity for glucose and galactose. Glucose galactose malabsorption is a hereditary disorder where these sugars are absorbed from the intestine at very slow rates. Other substances which do not share their pathway, e.g., fructose, are well absorbed. If mutarotase is required for the absorption of glucose and galactose, its absence, due to a genetic disorder, would block their absorption, while fructose would be well absorbed. We report a patient who satisfied these criteria and exhibited no mutarotase in his jejunal biopsies. Sixteen controls and 3 cases who were diagnosed as having the disease had mutarotase present in their jejunal biopsies. The data constitute evidence for mutarotase participation in sugar transport, as well as elucidate the etiology of this disease.