Structural Requirements of D-Glucose for its Binding to Isolated Human Erythrocyte Membranes

Abstract

KAHLENBEWC, A., and DQLANSKY, D. Structural requirements of glucose for its binding to isolated human erythrocyte membranes. Can. J. Bischem.The inhibition by various derivatives of D-glucose of the stereospecific uptake of this sugar by isolated human erythrocyte membranes was determined. Single changes at each of the five hydroxyi groups of D-glucose, except for the 2-deoxy and 6-deoxy derivatives, resulted in a variable decrease in the binding afinity of the sugar which was dependent upon the nature and locus of the alteration. In addition, the presence of the pyranose ring oxygen is required for optimal binding. The largest decrease in afinity effected by a single change of any s f the three hydroxyl groups of D-glucose which participate in the binding reaction (i.e. those at carbons 1,3. and 4) was obtained by the removal or derivatization of the anomeric (C-l) hydroxyl. A similar decrease in binding afinity was obtained upon sulfur substitution of the ring oxygen. The results are interpreted as indicating that the binding of D-glucose to its erythrocyte membrane acceptor site is probably mediated by hydrogen bonds between this membrane component and the hydroxyl groups at carbons 1, 3, and 4 of D-gliucose and the pyranose ring oxygen.

Conformational changes in human red cell membrane proteins induced by sugar binding

“…Since these were uptake experiments, the results were interpreted as indicative of competition at the extracellular site; indeed, many of the inhibitors were nontransportable sugars. Their results are in general agreement with those of Kahlenberg and Dolansky (1972) in showing the importance of H-bonding at C-1, C-3 and C-4. Barnett et al (1973Barnett et al ( , 1975 point out that bulky substituents can be accommodated at C-4 and C-6 and suggest that both C-4 and C-6 are readily accessible from the solution, whereas the other carbons are in close apposition to the site.…”

“…Quiocho (1986) points out that bilobal structures comprise a large proportion of carbohydrate binding proteins and gives several examples of conformational changes that follow apposition of the two domains around the sugar. The features that characterize both the GBP and the MBP fit well with the characteristics of the glucose binding site worked out by Kahlenberg and Dolansky (1972) and Barnett et al (1973). The arabinose-binding protein, whose structure is similar to the E. coti GBP and MBP has been sequenced and found to have homologous ranges, both in sequence and hydropathy analysis, to the red cell glucose transport protein (Mueckler, 1989).…”

“…In order to show that the effect is specific to the D-maltose binding site, we have studied several other disaccharides, not only to confirm the specificity of the D-maltose site, but also to give us further information about the sugar substituents which determine the DBDS effect. Kahlenberg and Dolansky (1972) determined the effect of individual H-bonding sites on the affinity of D-glucose binding to the external site in the red cell by systematic substitution of the glucose hydroxyls. They concluded that H-bonding to the hydroxyls at carbons 1, 3 and 4 of D-glucose and the pyranose ring oxygen were the most important determinants of the binding process and suggested that all the hydroxyls might play a role.…”

“…Although all three sugars in this group exhibit both biphasic kinetics and the DBDS effect, the fluorescence enhancement of lactose (galacto) is much less than that of cellobiose (gluco), and in lactulose (galacto) the fluorescence is quenched. The D-glucose site seems to be more sensitive to the galactose/ glucose difference, since Kahlenberg and Dolansky (1972) have shown that the KD of the D-galactose/ membrane complex is 90/XM, as compared to 27/xM for the D-glucose/membrane complex.…”

Maltosyl isothiocyanate: an affinity label for the glucose transporter of the human erythrocyte membrane. 2. Identification of the transporter

“…Furthermore, evidence exists which suggests that there are approximately 300 000 copies of each transporter per cell (Avruch & Fairbanks, 1972;Ho & Guidotti, 1975), although the number of anion transporters is unsettled (Rakitzis et al., 1978). In addition, it has been reported that external proteolysis under conditions which lead to conversion of band 3 to fragments of approximately 55 000 and 40 000 molecular weight does not inhibit the functions of the transporters for glucose Carter et al, 1973;Kahlenberg et al, 1972), cations (Avruch & Fairbanks, 1972;Wagner et al, 1974), or anions (Rothstein et al, 1976). Despite these similarities, in intact cells each transport function appears to be independent of the others.…”