Anomeric preference of fluoroglucose exchange across human red-cell membranes. 19F-n.m.r. studies

Abstract

The rates of exchange across the human red-cell membrane of the alpha- and beta-anomers of the glucose derivative 3-fluoro-3-deoxy-D-glucose (3FG) were measured, under equilibrium-exchange conditions, using a 19F-n.m.r.-magnetization-exchange procedure. In experiments carried out over a range of 3FG concentrations (3.4-113 mM), the alpha-anomer was found to be transported with a smaller Km (greater apparent affinity) than the beta-anomer. In two experiments carried out at 34 and 37 degrees C the ratio (alpha/beta) of the Michaelis constants for exchange was 0.75 +/- 0.07 and 0.83 +/- 0.07 respectively and the Vmax for 3FG exchange was 28 +/- 3 and 33 +/- 3 mmol.s-1.litre of cells-1 respectively. In several experiments carried out at a single 3FG concentration (17 mM) and at 37 degrees C, using red cells from four individuals, the rate of exchange of the alpha-anomer across the membrane was significantly higher than that of the beta-anomer. The weighted mean value of the above-mentioned ratio was 0.79 +/- 0.07 for the four donors.

The Polar Hydrophobicity of Fluorinated Compounds

“…Transport studies of 1‐, 2‐, 3‐, 4‐, and 6‐monodeoxyfluoro‐ D ‐glucose across the RBC membrane have been performed to probe the binding requirement for transmembrane transport and anomeric preferences for mediated transport through the RBC membrane have been noted 67–70. 2‐Deoxy‐2‐fluoro‐ D ‐glucose (2‐DFG) and 3‐deoxy‐3‐fluoro‐ D ‐glucose (3‐DFG) cross the erythrocyte membrane at rates very similar to that of glucose, while permeabilities for the 4‐ and 6‐substituted derivatives (4‐DFG and 6‐DFG) are roughly halved 68.…”

Model of 2,3-bisphosphoglycerate metabolism in the human erythrocyte based on detailed enzyme kinetic equations: equations and parameter refinement

“…The Mass Action ratio for the reaction catalysed by TPI in the normal in i o state has been reported by many different authors to be $ 3 (See Table 3.1 in [31]), while the equilibrium constant is around 20 [32,33]. The reason for this discrepancy is unclear given the very high catalytic capacity of TPI ; TPI has been described as the ' perfect enzyme ' [34].…”

“…In human erythrocytes, glucose transport across the plasma membrane is 250-1000 times the rate of glucose utilization [31][32][33]. Hence k i was set to $ 1 s −" .…”

Determination of glucose exchange rates and permeability of erythrocyte membrane in preeclampsia and subsequent oxidative stress-related protein damage using dynamic-19F-NMR

“…Whilst the “Overdetermined” 1D EXSY pulse sequence of Bulliman et al (1989) has also been used to study erythrocytes (Potts and Kuchel 1992), the more complex matrix diagonalisation methods are different to those employed in most other exchange applications. Selective inversion was the 1D method of choice in this investigation (Robinson et al 1985).…”