title: Occurrence and characterization of fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase in Euglena gracilis.
abstract: 1. Fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase occurred in Euglena gracilis SM-ZK, and is located in cytosol. 2. Fructose 6-phosphate, 2-kinase and fructose 2,6-bisphosphatase were partially purified, and both enzyme activities were not separated during the partial purification. 3. The pH optimum for fructose 6-phosphate, 2-kinase activity was 7.0. The saturation curve of the enzyme activity for ATP concentration was hyperbolic, and the Km value for the substrate was 0.88 mM. On the other hand, the saturation curve of the enzyme activity for fructose 6-phosphate concentration was sigmoidal, and the K0.5 value for the substrate was 70 microM. 4. The pH optimum for fructose 2,6-bisphosphatase activity was 6.5. The saturation curve for fructose 2,6-bisphosphate concentration was sigmoidal, and the K0.5 value for the substrate was 1.29 microM. Fructose 2,6-bisphosphate showed a substrate inhibition at high concentration over 5 microM, and the enzyme activity was completely inhibited by 20 microM of fructose 2,6-bisphosphate.
authors.affiliation: Department of Agricultural Chemistry, University of Osaka Prefecture, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Enomoto
authors.forename: K
authors.initials: K
authors.lastname: Kakihara
authors.forename: K
authors.initials: K
authors.lastname: Miyatake
authors.forename: S
authors.initials: S
authors.lastname: Kitaoka
mesh_terms: D000818:Animals; D003600:Cytosol / Q000201:enzymology; D005056:Euglena gracilis / Q000201:enzymology*; D005635:Fructosediphosphates / Q000494:pharmacology; D005943:Gluconeogenesis; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*
chemical_list: D005635:Fructosediphosphates; C027652:fructose 2,6-diphosphate; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases