Digestion and absorption of disaccharides in man

Abstract

MUSCLE PHOSPHOGLYCERATE KINASE411 glycolytic pathway but contained triose phosphate isomerase.2. A new assay method for studying the phos- phoglycerate-kinase reaction in the forward direc- tion was developed.T'he method has the advantage that it can be used with partially purified enzyme preparations containing triose phosphate isomerase and a-glycerophosphate dehydrogenase.The assay method also facilitated an independent study of inhibitors and metal ions in the enzyme reactions.3. Phosphoglycerate kinase is activated by Mg2+ and Mn2+ ions, and by no other metal ions tested.It reacts specifically with adenosine and di- and tri-phosphate, but with no other nucleotides.4. The study of the effect of various thiolbinding agents on the muscle and yeast phosphoglycerate kinases revealed that the muscle phospho- glycerate kinase is a sulphydryl enzyme whereas the yeast enzyme is not.5. The Michaelis constants for the various substrates and activators obtained with the muscle enzyme are similar to the values obtained with the yeast enzyme.These values are also in good agree- ment with the data originally reported by Bucher (1947).The Michaelis constants of the muscle and yeast enzymes for phosphoglyceryl phosphate have been determined independently by an isotopic method.We thank Miss Anne Savacool for competent technical assistance during certain aspects of this work.One of us (D.R.) wishes to thank the Graduate Division of Hahne- mann Medical College