A second hexokinase (EC 2.7.1.1) was obtained from pea seed (Pisum sativum L. var. Progress No. 9) extracts. The enzyme, termed hexokinase II, had a high affinity (K(m), 48 micromolar) for glucose and a relatively low affinity (K(m), 10 millimolar) for fructose. The K(m) for MgATP was 86 micromolar. Mg(2+) was required for activity, but excess Mg(2+) was inhibitory. MgADP inhibited hexokinase I...

BACKGROUND Hexokinase is one of the key enzymes of glycolysis and catalyzes the phosphorylation of glucose to glucose-6-phosphate. Red blood cell-specific hexokinase is transcribed from HK1 by use of an erythroid-specific promoter. The aim of this study was to investigate the molecular basis for hexokinase deficiency in a patient with chronic hemolysis. DESIGN AND METHODS Functional studies w...

1. Crystalline hexokinase has been isolated from baker's yeast. 2. Crystalline hexokinase is a protein of albumin type of a molecular weight of 96,000. Its isoelectric point is at about pH 4.8. 3. The method of isolation consists in separating the proteins of an aqueous extract of toluene-treated yeast by means of fractional precipitation with ammonium sulfate and with alcohol. 4. The procedure...

Hexokinase plays a key role in regulating cell energy metabolism. Hexokinase is mainly particulate, bound to the mitochondrial outer membrane in brain and tumour cells. We hypothesized that the intracellular pH (pH1) controls the intracellular distribution of hexokinase. Using the SNB-19 glioma cell line, pH1 variations were imposed by incubating cells in a high-K+ medium at different pH values...

A 27-year-old woman with severe chronic hemolytic anemia was found to have reduced red cell hexokinase activity when the degree of reticulocytosis was considered. This enzyme had normal pH-dependent activity, normal Km for glucose, fructose, and mannose, normal Km for Mg adenosine triphosphate (ATP)2- and Ki for glucose-1,6-diphosphate. Furthermore, the pH-dependence and orthophosphate dependen...

In a patient with nonspherocytic hemolytic anemia, a hexokinase deficiency was detected in the red cells (residual activity about 25% of normal) and in blood platelets (20%-35% of normal activity). Although the total hexokinase activity in lymphocytes was normal, the amount of hexokinase type I was decreased to about 50% of normal. However, the deficiency was compensated for by the appearance o...

The purification is described of rat hepatic hexokinase type III and kidney hexokinase type I on a large scale by using a combination of conventional and affinity techniques similar to those previously used for the purification of rat hepatic glucokinase [Holroyde, Allen, Storer, Warsy, Chesher, Trayer, Cornish-Bowden & Walker (1976) Biochem. J. 153, 363-373] and muscle hexokinase type II [Holr...

The mechanism of the hexokinase reaction has been the subject of numerous investigations in recent years (l-5). ijgren and Engstrijm reported the incorporation of Pa from labeled adenosine triphosphate (ATP) into the phosphoserine moiety of hexokinase in the absence of substrate glucose and concluded that an enzyme-phosphate intermediate participated in the reaction (2). Gamble and Najjar, howe...