Anomeric Specificity of Glucose Metabolism in Health and Disease

Malaisse, Willy

doi:10.1179/acb.2001.050

Cited by 1 publication

(1 citation statement)

References 29 publications

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“…Incidentally, the present results indicate that the possible channelling of -D-fructose-6-phosphate, specifically generated by phosphoglucoisomerase, 14 between the latter enzyme and phosphofructokinase 15 does not affect to any significant extent the estimation of 3 glucose anomers values which are not significantly different from the corresponding experimental data, it was necessary to considerably increase the fractional escape of -D-glucose-6-phosphate from the postulated process of enzyme-to-enzyme channelling in the islets incubated at the low concentration of the hexose (2.8 mM) when compared to the situation recently characterized 1 in islets exposed to a normal concentration of D-glucose (8.3 mM). It should be emphasized that in all these models, prior information on the phosphorylation rate of D-glucose, cell content in D-glucose-6-phosphate and D-fructose-6-phosphate and flux through the pentose phosphate pathway in intact islets exposed to the anomers of D-glucose, 11,16 as well as on the intrinsic properties of phosphoglucoisomerase, 17,18 were all also duly taken into account.…”

Section: Discussionmentioning

confidence: 99%

Impaired enzyme-to-enzyme channelling between hexokinase isoenzyme(s) and phosphoglucoisomerase in rat pancreatic islets incubated at a low concentration ofD-glucose

Zhang¹,

Jijakli²,

Courtois³

et al. 2004

Cell Biochem. Funct.

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It was recently proposed that in rat pancreatic islets exposed to 8.3 mM D-glucose, alpha-D-glucose-6-phosphate undergoes enzyme-to-enzyme channelling between hexokinase isoenzyme(s) and phosphoglucoisomerase. To explore the identity of the hexokinase isoenzyme(s) involved in such a tunnelling process, the generation of 3HOH from the alpha- and beta-anomers of either D-[2-3H]glucose or D-[5-3H]glucose was now measured over 60 min incubation at 4 degrees C in pancreatic islets exposed only to 2.8 mM D-glucose, in order to decrease the relative contribution of glucokinase to the phosphorylation of the hexose. Under these experimental conditions, the ratio for 3HOH production from D-[2-3H]glucose/D-[5-3H]glucose at anomeric equilibrium (39.7 +/- 11.6%) and the beta/alpha ratios for the generation of 3HOH from either the D-[2-3H]glucose anomers (70.9 +/- 12.6%) or the D-[5-3H]glucose anomers (59.6 +/- 12.4%) indicated that a much greater fraction of alpha-D-glucose-6-phosphate escapes from the process of enzyme-to-enzyme channelling in the islets exposed to 2.8 mM, rather than 8.3 mM D-glucose. These findings suggest, therefore, that the postulated process of enzyme-to-enzyme channelling involves mainly glucokinase.

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