Carbohydrate metabolism in the human fetal and new-born tissue, with special reference to glycogen

Abstract

Glycogen has been extracted from human fetal livers ranging in age from 13 to 26 weeks. The average chain lengths have been determined by a-amylolysis and periodate oxidation and the average exterior chain lengths by B-amylolysis. The structures of liver glycogens from baboon, mouse, rabbit and several mature humans have also been determined. The absorption spectra of someglycogen-iodine complexes have been recorded and also glycogen values have been determined by the reaction with concanavalin A. The development of glycogen in the human fetal liver is discussed in relation to other mammalian species. The activities of the enzymes glucose-6-phosphatase (D-glucose-6-phosphate phosphohydrolase), phosphoglucomutase (D-glucose-1,6-diphosphate: D-glucose-l-phosphate phosphotransferase), and phosphoglucoisomerase (D-glucose-6-phosphate ketol isomerase) in the human fetus have been studied. The liver glycogens from four cases of suspected glycogen storage disease have been isolated and the structures determined as previously described. An electrophoretic and chromatographic study has been made of sugars in the urine of another case, where the patient lacked several intestinal enzymes.The action of glucamylase and a commercial amyloglucosidase preparation ("Diazyme") on glycogen has been examined. The glucamylase and B -amylase limit dextrins of glycogen have been isolated and their average chain lengths determined.