HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 7, 4531-4535, February 14, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/7/4531    most recent M206730200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jijakli, H. Articles by Malaisse, W. J. Search for Related Content PubMed PubMed Citation Articles by Jijakli, H. Articles by Malaisse, W. J. Social Bookmarking                      What's this?

Anomeric Specificity of the Stimulatory Effect of D-Glucose on D-Fructose Phosphorylation by Human Liver Glucokinase^*

Hassan Jijakli, Philippe Courtois, Hai-Xia Zhang, Abdullah Sener, and Willy J. Malaisse

From the Laboratory of Experimental Medicine, Brussels Free University, B-1070 Brussels, Belgium

D-Glucose was recently reported to stimulate D-fructose phosphorylation by human B-cell glucokinase. The present study aims at investigating the anomeric specificity of such a positive cooperativity. The -anomer of D-glucose was found to increase much more markedly than -D-glucose the phosphorylation of D-fructose by human liver glucokinase. Such an anomeric preference diminished at high concentrations of the D-glucose anomers, i.e. when the effect of the aldohexose upon D-fructose phosphorylation became progressively less marked. A comparison between the effects of the two anomers of D-glucose and those of equilibrated D-glucose upon D-fructose phosphorylation by human liver glucokinase indicated that the results obtained with the equilibrated aldohexose were not significantly different from those expected from the combined effects of each anomers of D-glucose. In isolated rat islets incubated for 60 min at 4 °C, -D-glucose (5.6 mM), but not -D-glucose (also 5.6 mM), augmented significantly the conversion of D-[U-¹⁴C]fructose (5.0 mM) to acidic radioactive metabolites. Likewise, in islets prelabeled with ⁴⁵Ca and perifused at 37 °C, D-fructose (20.0 mM) augmented ⁴⁵Ca efflux and provoked a biphasic stimulation of insulin release from islets exposed to -D-glucose (5.6 mM), while inhibiting ⁴⁵Ca efflux and causing only a sluggish and modest increase in insulin output from islets exposed to -D-glucose (also 5.6 mM). The enhancing action of D-glucose upon D-fructose phosphorylation by glucokinase thus displays an obvious anomeric preference for -D-glucose, and such an anomeric specificity remains operative in intact pancreatic islets.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati