Inhibition by saccharin of glucose-6-phosphatase: effects of alloxan in vivo and deoxycholate in vitro.
Inhibition by saccharin of rat liver glucose-6-phosphatase (EC 3.1.3.9) generally decreased as the pH increased in the range pH 4-8. This pattern was exhibited by homogenates from control and alloxan-treated animals assayed each in the absence and presence of 0.2% (w/v) deoxycholate. Saccharin inhibited in competitive fashion with respect to glucose-6-phosphate (glucose-6-P). There was a small increase in Km (glucose-6-P) but not K1 (saccharin) values in alloxan-treated rats when assays were conducted in the absence of deoxycholate. In the presence of this detergent there was no significant difference in these kinetic parameters between the alloxan-treated and control groups. Deoxycholate decreased Km (glucose-6-P) and increased K1 (saccharin) values. Calculations using these kinetic parameters indicate that, under usual hepatic glucose-6-P concentrations and relatively high levels of saccharin in liver, the inhibition by saccharin of glucose-6-phosphatase is unlikely to be of major significance in vivo.
D000496:Alloxan / Q000494:pharmacology*; D000818:Animals; D001667:Binding, Competitive; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D003840:Deoxycholic Acid / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology; D005952:Glucose-6-Phosphatase / Q000037:antagonists & inhibitors*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009929:Organ Size; D051381:Rats; D012439:Saccharin / Q000494:pharmacology*
D001786:Blood Glucose; D003840:Deoxycholic Acid; D000496:Alloxan; D005952:Glucose-6-Phosphatase; D012439:Saccharin