scholarly journals Structural requirements for binding to the sugar-transport system of the human erythrocyte

1973 ◽  
Vol 131 (2) ◽  
pp. 211-221 ◽  
Author(s):  
J. E. G. Barnett ◽  
G. D. Holman ◽  
K. A. Munday
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Sugar Transport ◽  
Hydroxyl Group ◽  
Structural Requirements ◽  
Glucose Molecule ◽  
Inhibition Constants ◽  
Polar Substituents ◽  
Sugar Derivatives ◽  
Potential Substrate

The structural requirements for binding to the glucose/sorbose-transport system in the human erythrocyte were explored by measuring the inhibition constants, Ki, for specifically substituted analogues of d-glucose when l-sorbose was the penetrating sugar. Derivatives in which a hydroxyl group in the d-gluco configuration was inverted, or replaced by a hydrogen atom, at C-1, C-2, C-3, C-4 or C-6 of the d-glucose molecule, all bound to the carrier, confirming that no single hydroxyl group is essential for binding to the carrier. The binding and transport of 1-deoxy-d-glucose confirmed that the sugars bind in the pyranose form. The relative inhibition constants of d-glucose and its deoxy, epimeric and fluorinated analogues are consistent with the combination of β-d-glucopyranose with the carrier by hydrogen bonds at C-1, C-3, probably C-4, and possibly C-6 of the sugar. Both polar and non-polar substituents at C-6 enhance the affinity of d-glucose derivatives relative to d-xylose, and d-galactose derivatives relative to l-arabinose, and it is suggested that the carrier region around C-6 of the sugar may contain both hydrophobic and polar binding groups. The spatial requirements at C-1, C-2, C-3, C-4 and C-6 were explored by comparing the relative binding of d-glucose and its halogeno and O-alkyl substituents. The carrier protein closely approaches the sugar except at C-3 in the d-gluco configuration, C-4 and C-6. d-Glucal was a good inhibitor, showing that a strict chair form is not essential for binding. 3-O-(2′,3′-Epoxypropyl)-d-glucose, a potential substrate-directed alkylating agent, bound to the carrier, but did not inactivate it.

scholarly journals Evidence for two asymmetric conformational states in the human erythrocyte sugar-transport system

1975 ◽  
Vol 145 (3) ◽  
pp. 417-429 ◽  
Author(s):  
J E Barnett ◽  
G D Holman ◽  
R A Chalkley ◽  
K A Munday
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Human Erythrocyte ◽  
Partition Coefficients ◽  
External Medium ◽  
Sugar Transport ◽  
Conformational States ◽  
Glucose Transport System ◽  
Oil Water

6-O-methyl-, 6-O-propyl-, 6-O-pentyl- and 6-O-benzyl-D-galactose, and 6-O-methyl-, 6-O-propyl- and 6-O-pentyl-D-glucose inhibit the glucose-transport system of the human erythrocyte when added to the external medium. Penetration of 6-O-methyl-D-galactose is inhibited by D-glucose, suggesting that it is transported by the glucose-transport system, but the longer-chain 6-O-alkyl-D-galactoses penetrate by a slower D-glucose-insensitive route at rates proportional to their olive oil/water partition coefficients. 6-O-n-Propyl-D-glucose and 6-O-n-propyl-D-galactose do not significantly inhibit L-sorbose entry or D-glucose exit when present only on the inside of the cells whereas propyl-beta-D-glucopyranoside, which also penetrates the membrane slowly by a glucose-insensitive route, only inhibits L-sorbose entry or D-glucose exit when present inside the cells, and not when on the outside. The 6-O-alkyl-D-galactoses, like the other nontransported C-4 and C-6 derivatives, maltose and 4,6-O-ethylidene-D-glucose, protect against fluorodinitrobenzene inactivation, whereas propyl beta-D-glucopyranoside stimulates the inactivation. Of the transported sugars tested, those modified at C-1, C-2 and C-3 enhance fluorodinitrobenzene inactivation, where those modified at C-4 and C-6 do not, but are inert or protect against inactivation. An asymmetric mechanism is proposed with two conformational states in which the sugar binds to the transport system so that C-4 and C-6 are in contact with the solvent on the outside and C-1 is in contact with the solvent on the inside of the cell. It is suggested that fluorodinitrobenzene reacts with the form of the transport system that binds sugars at the inner side of the membrane. An Appendix describes the theoretical basis of the experimental methods used for the determination of kinetic constants for non-permeating inhibitors.

Specificity of sugar transport by the intestine of the hamster

1960 ◽  
Vol 198 (1) ◽  
pp. 99-102 ◽  
Author(s):  
T. Hastings Wilson ◽  
Bernard R. Landau
Keyword(s):  
Small Intestine ◽  
Transport System ◽  
Concentration Gradient ◽  
Sugar Transport ◽  
Intestinal Wall ◽  
Sugar Derivatives

The specificity of the sugar transport system of the hamster small intestine was tested with 20 sugars and sugar derivatives not previously tested in this system. The absorption of sugars across the intestinal wall against a concentration gradient was tested with the everted sac technique in vitro. 3-Deoxyglucose, 4-0-methylgalactose, 6-deoxy-6-fluoroglucose and α-methylglucoside were transported while a variety of other sugars were not. From the data derived from the study of a total of 49 sugars tested in this system, certain generalizations are made as to the structural limitations of the sugar-absorbing capacity of the hamster intestine.

scholarly journals An explanation of the asymmetric binding of sugars to the human erythrocyte sugar-transport systems

1973 ◽  
Vol 135 (3) ◽  
pp. 539-541 ◽  
Author(s):  
J. E. G. Barnett ◽  
G. D. Holman ◽  
K. A. Munday
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Sugar Transport ◽  
Transport Systems

6-O-Alkyl-d-galactoses competitively inhibit the erythrocyte sugar-transport system when added to the outside of the cells, but not to the inside. n-Propyl β-d-glucopyranoside competitively inhibits the system on the inside of the cells, but not on the outside. A model for sugar transport is proposed.

Renal sugar transport in the winter flounder. III. Two glucose transport systems

1977 ◽  
Vol 232 (3) ◽  
pp. F227-F234 ◽  
Author(s):  
A. Kleinzeller ◽  
G. R. Dubyak ◽  
P. M. Griffin ◽  
E. M. McAvoy ◽  
J. M. Mullin ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Glucose Transport ◽  
Transport System ◽  
Sugar Transport ◽  
Winter Flounder ◽  
Transport Systems ◽  
Renal Tubules ◽  
Pyranose Ring ◽  
Structural Requirements ◽  
Specificity Pattern

Teased renal tubules of the winter flounder (Pseudopleuronectes americanus) were employed to investigate the structural requirements for two pathways of D-glucose transport which take place preponderantly across the basal (antiluminal) face of renal cells. 1) An inhibition analysis of the equilibrating, Na-independent and phlorizin-sensitive transport of the nonmetabolizable methyl-alpha-D-glucoside (0.1 and 0.5 mM), with 20 glucose analogs (5 mM), was employed to establish the structural requirements for the substrate-carrier interaction: a (pyranose) ring, oxygen, or F at C1, C2-OH, C3-OH, and C4-OH (all axial, 1C model). Some interaction may also occur at C6-OH. D-Glucose shares this transport system. Hydrogen bonding between the oxygens and the carrier is suggested. 2) The phloretin- and phlorizin-sensitive, ouabain-insensitive transport of D-glucose, 2-deoxy-D-glucose, and D-mannose is associated with considerable phosphorylation. The three sugars mutually compete for a shared transport site. The specificity pattern characterizing the transport system defines the following structural requirements: a (pyranose) ring, a free C1-OH, C3-OH, and C4-OH (both axial) and possibly C6-OH. Hydrogen bonding between the carrier and the oxygens at C3, C4, and C6, and covalent bonding at C1 is suggested.

Lead and calcium transport in human erythrocyte

1999 ◽  
Vol 18 (5) ◽  
pp. 327-332 ◽  
Author(s):  
J V Calderón-Salinas ◽  
M A Quintanar-Escorcia ◽  
M T González-Martínez ◽  
C E Hernández-Luna
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Calcium Transport ◽  
Human Erythrocytes ◽  
The Other ◽  
Erythrocyte Ghosts ◽  
Passive Transport ◽  
Ca Uptake

In this paper we report the lead (Pb) and calcium (Ca) uptake by erythrocyte ghosts. In both cases the transport was carried out by a passive transport system with two kinetic components (Michaelis-Menten and Hill). Pb and Ca were capable of inhibiting the transport of the other metal in a non-competitive way. Under hyperpolarization, the uptakes of Ca and Pb were enhanced and the Michaelis-Menten component prevailed. Both Ca and Pb uptakes were inhibited by N-ethyl-maleimide to the same extent. These results indicate that Pb and Ca share the same permeability pathway in human erythrocytes and that this transport system is electrogenic.

scholarly journals The interaction of 3-deoxy-3-fluoro-d-glucose with the hexose-transport system of the human erythrocyte

1973 ◽  
Vol 135 (4) ◽  
pp. 773-777 ◽  
Author(s):  
G. J. Riley ◽  
N. F. Taylor
Keyword(s):  
Kinetic Parameters ◽  
Erythrocyte Membrane ◽  
Transport System ◽  
Dissociation Energy ◽  
Human Erythrocyte ◽  
Optical Method ◽  
Hexose Transport ◽  
Human Erythrocyte Membrane ◽  
Significant Release ◽  
Glucose Carrier

1. By using an optical method the kinetic parameters of hexose transport across the human erythrocyte membrane were determined for several sugars. The series of half-saturated constants is as follows: 3-deoxy-3-fluoro-d-glucose = 3-O-methyl-d-glucose <d-glucose<d-mannose <3-deoxy-d-glucose<d-galactose<l-arabinose. 2. Estimations of the dissociation energy of the 3-deoxy-3-fluoro-d-glucose–carrier and d-glucose–carrier complexes suggest that the binding of the two sugars to the transport system is equivalent. 3. Incubation of the erythrocytes with 3-deoxy-3-fluoro-d-glucose results in a small but significant release of F−anion. Cells treated in this way lose their ability to transport glucose.

scholarly journals Intramolecular Nitrile Oxide—Alkene Cycloaddition of Sugar Derivatives with Unmasked Hydroxyl Group(s).

ChemInform ◽  
2007 ◽  
Vol 38 (29) ◽  
Author(s):  
Tony K. M. Shing ◽  
Wai F. Wong ◽  
Hau M. Cheng ◽  
Wun S. Kwok ◽  
King H. So
Keyword(s):  
Nitrile Oxide ◽  
Hydroxyl Group ◽  
Sugar Derivatives
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