Utility of 3-O-methyl-N-acetyl-D-glucosamine, an N-acetylglucosamine Kinase Inhibitor, for Accurate Assay of Glucokinase in Pancreatic Islets and Liver

Enzyme Protein. 1994-1995;48(3):135-42. doi: 10.1159/000474980.

Abstract

Glucokinase, an enzyme that catalyzes the phosphorylation of glucose, constitutes the key regulatory step in glucose metabolism in pancreatic islets and liver. We found that 3-O-methyl-N-acetyl-D-glucosamine (3-O-methyl-GlcNAc) potently inhibits glucose phosphorylation by N-acetylglucosamine kinase whereas glucokinase is not at all affected by this hexosamine. The addition of 3-O-methyl-GlcNAc to the assay system for glucokinase in rat liver extracts, which contain a high activity of glucokinase (glucose as substrate) relative to N-acetylglucosamine kinase (N-acetyl-D-glucosamine as substrate), affected neither Km nor Vmax values of glucokinase. On the other hand, both Km and Vmax values of glucokinase in rat pancreatic islet extracts, in which N-acetylglucosamine kinase activity is higher than glucokinase activity, were significantly lowered by the use of 3-O-methyl-GlcNAc as an inhibitor of N-acetylglucosamine kinase.

MeSH terms

  • Acetylglucosamine / analogs & derivatives*
  • Acetylglucosamine / pharmacology
  • Animals
  • Enzyme Inhibitors / pharmacology*
  • Female
  • Glucokinase / isolation & purification
  • Glucokinase / metabolism*
  • Glucose / metabolism
  • Islets of Langerhans / enzymology*
  • Kinetics
  • Liver / enzymology*
  • Phosphorylation
  • Phosphotransferases (Alcohol Group Acceptor) / antagonists & inhibitors*
  • Phosphotransferases (Alcohol Group Acceptor) / isolation & purification
  • Rats
  • Rats, Wistar
  • Substrate Specificity

Substances

  • Enzyme Inhibitors
  • methyl-2-acetamido-2-deoxy-D-glucopyranoside
  • Phosphotransferases (Alcohol Group Acceptor)
  • Glucokinase
  • N-acetylglucosamine kinase
  • Glucose
  • Acetylglucosamine