Anomeric preference of fluoroglucose exchange across human red-cell membranes. 19F-n.m.r. studies.
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.
Potts
J R
JR
Department of Biochemistry, University of Sydney, N.S.W., Australia.
Kuchel
P W
PW
D001692:Biological Transport; D002463:Cell Membrane Permeability; D003847:Deoxyglucose / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry; D004910:Erythrocyte Membrane / Q000378:metabolism*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009004:Monosaccharide Transport Proteins / Q000097:blood*; D013237:Stereoisomerism
D009004:Monosaccharide Transport Proteins; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose