| Abstrakt: |
The anomeric specificity of d-glucose metabolism in intact hepatocytes remains a matter of debate. This issue was further investigated in the present study, which is based on the quantification of the α- and β-anomers of the 13C-enriched isotopomers of d-glucose generated by rat liver cells exposed to either d-[1-13C] fructose or d-[2-13C] fructose in the presence of D2O. The d-[1-13C]glucose/d-[6-13C]glucose paired ratios found in the cells exposed to d-[1-13C] fructose and the d-[2-13C]glucose/d-[5-13C]glucose paired ratios found in the cells exposed to d-[2-13C] fructose yielded a paired β/α ratio averaging (mean ± S.E.M.) 79.3 ± 6.1%. In the case of the isotopomers of d-glucose formed by gluconeogenesis, the d-[2-13C]glucose/d-[5-13C]glucose and d-[3-13C]glucose/d-[4-13C]glucose paired ratios found in cells exposed to d-[1-13C] fructose, as well as the d-[1-13C]glucose/d-[6-13C]glucose and d-[3-13C]glucose/d-[4-13C]glucose paired ratios found in cells exposed to d-[2-13C]fructose, yielded an α/β paired ratio averaging 75.0 ± 5.8%. Last, in the cells exposed to d-[2-13C]fructose, the β/α ratio for the C2-deuterated isotopomers of d-[2-13C]glucose represented 78.9 ± 3.7% of that for the C5-deuterated isotopomers of d-[5-13C]glucose. The three values representative of the anomeric specificity of d-glucose production by liver cells were not significantly different from one another, with an overall mean value of 76.9 ± 3.6%. These findings unambiguously document that the anomeric specificity of phosphoglucoisomerase is operative in intact hepatocytes, resulting in a preferential output of the α-anomer of 13C-enriched d-glucose under the present experimental conditions (Mol Cell Biochem 266: 145150, 2004) [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink