Transport of Sugars and Amino Acids in Bacteria: II. Properties of Galactose- and Leucine-Binding Proteins

Abstract

The galactose- and leucine-binding proteins of Escherichia coli were obtained and their physicochemical properties were studied. Both proteins were homogeneous as judged by sedimentation behavior. Molecular weights of 35,000 and 36,000 were obtained for the galactose- and leucine-binding protein, respectively. Analyses for amino acid composition, inorganic phosphate, and pentose content are reported. The proteins were relatively heat- and acid-stable but were alkali-labile. No selective inhibitors for binding activity have been found so far. The nature of the complex of binding protein with substrate has been examined. The complex consisted of 1 molecule of substrate per molecule of protein.