Phosphorylation of D-glucosamine by rat liver glucokinase.
D-Glucosamine was found to be phosphorylated by a rat liver extract in the presence of a high concentration of glucose, which was formerly believed to be a strong competitive inhibitor of this reaction. Results suggested that glucosamine may be phosphorylated by high Km hexokinase, i.e. glucokinase [EC 2.7.1.2]. The enzyme involved was separated from specific N-acetyl-D-glucosamine kinase [EC 2.7.1.59]. The phosphorylation was not inhibited by a physiological level of glucose or glucose 6-phosphate, which strongly inhibited low Km hexokinase. The apparent Km of glucokinase for glucosamine was estimated as 8 mM, which is ten times that of low Km hexokinase.
D000818:Animals; D005941:Glucokinase / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D005958:Glucosephosphates / Q000494:pharmacology; D006593:Hexokinase / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D051381:Rats
D005958:Glucosephosphates; D007527:Isoenzymes; D006593:Hexokinase; D005941:Glucokinase; D005947:Glucose; D005944:Glucosamine