Open AccessChromatographic resolution and kinetic characterization of glucokinase from islets of Langerhans.
Author(s) -
M. D. Meglasson,
Pamela Trueheart Burch,
Donna K Berner,
Habiba Najafi,
Alan P. Vogin,
Franz M. Matschinsky
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.1.85
Subject(s) - glucokinase , hexokinase , islet , biochemistry , phosphotransferase , enzyme , chemistry , chromatography , affinity chromatography , hexose , biology , glycolysis , insulin , endocrinology
Glucokinase (ATP:D-glucose 6-phosphotransferase, EC 2.7.1.2) from rat islets of Langerhans was partially purified by chromatography on DEAE-Cibacron blue F3GA agarose. The enzyme eluted in two separate peaks. Sigmoidal rate dependence was found with respect to glucose (Hill coefficient = 1.5) for both enzyme fractions. Km values for glucose were 5.7 mM for the major fraction and 4.5 mM for the minor fraction. Neither fraction phosphorylated GlcNAc. A GlcNAc kinase (ATP:2-acetamido-2-deoxy-D-glucose 6-phosphotransferase, EC 2.7.1.59)-enriched fraction, prepared by affinity chromatography on Sepharose-N-(6-aminohexanoyl)-GlcNAc, had a Km of 25 microM for GlcNAc. Islet tissue also contained hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) eluting in multiple peaks. The results are consistent with the concept that glucokinase serves as the glucose sensor of pancreatic beta cells.