hexokinase


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hexokinase

 [hek″so-ki´nās]
an enzyme that catalyzes the transfer of a high-energy phosphate group of a donor to d-glucose, producing d-glucose-6-phosphate.

hex·o·ki·nase

(heks'ō-kī'nās),
A phosphotransferase present in yeast, muscle, brain, and other tissues that catalyzes the ATP-dependent phosphorylation of d-glucose and other hexoses to form d-glucose 6-phosphate (or other hexose 6-phosphates); the first step in glycolysis; a deficiency of hexokinase can result in hemolytic anemia and impaired glycolysis.

hexokinase

/hexo·ki·nase/ (hek″so-ki´nās) an enzyme that catalyzes the transfer of a high-energy phosphate group to a hexose, the initial step in the cellular utilization of free hexoses. The enzyme occurs in all tissues as various isozymes with varying specificities; the liver isozyme (type IV) is specific for glucose and is often called glucokinase.

hexokinase

[hek′səkī′nās]
Etymology: Gk, hex, six, glykys, sweet, kinein, to move, ase, enzyme
a transferase enzyme present in all tissue that catalyzes the transfer of a phosphate group from adenosine triphosphate to glucose 6-phosphate. It is also found in yeast.

hex·o·ki·nase

(heks'ō-kī'nās)
A phosphotransferase present in yeast, muscle, brain, and other tissues that catalyzes the phosphorylation of d-glucose and other hexoses to form d-glucose 6-phosphate (or other hexose 6-phosphate) (phosphate is transferred from ATP, which is converted to ADP); the first step in glycolysis; a deficiency of hexokinase can result in hemolytic anemia and impaired glycolysis.

muscle enzymes

the table lists some of the most often-mentioned enzymes present in skeletal muscle, with their locations and functions. Apart from actomyosin and myosin ATPases which are associated with the contractile mechanism, they are by no means specific to muscle, being present and highly active also in other tissues. See also Krebs cycle, muscle fibre types.
Table 1: Muscle enzymes
Name SiteCatalyses…
Actomyosin ATPase (amATPase) myosin head groups hydrolysis (Mg-dependent and triggered by rise in [Ca2+]) of terminal phosphate group of ATP when head-group is in interaction with actin, releasing energy that powers force- generation. (Compare myosin ATPase)
Creatine kinase (CK) cytoplasm transfer of phosphate group from creatine phosphate to ADP, producing ATP and creatine. Isoenzymes can be distinguished in blood when either skeletal or cardiac muscle has been damaged.
Hexokinase (HK) cytoplasm 'capture' of glucose after uptake from the blood, by conversion to the impermeant glucose 6-phosphate, in type 1 muscle fibres, which utilize glucose directly.
Lactate dehydrogenase (LDH) cytoplasm reduction of pyruvate to lactate when oxygen tension is low, and the converse when it is high. Isoenzymes can be distinguished in blood when either skeletal or cardiac muscle has been damaged.
Myosin ATPase (mATPase) myosin head groups hydrolysis (Ca2+ dependent, Mg2+ independent) of terminal phosphate group of ATP by head group alone, not interacting with actin (so not contraction-producing: cf actomyosin ATPase). Basic histochemical marker for fast vs. slow fibres.
Phosphofructokinase (PFK) cytoplasm conversion of fructose 6-phosphate to fructose 1,6-diphosphate; rate-limiting for glycolysis, and sensitive to very many stimulatory and inhibitory influences.
Phosphorylase (PPL) cytoplasmremoval of hexose units, one at a time, from glycogen, to form glucose 1-phosphate: rate-limiting enzyme of, and histochemical marker for, glycogenolysis.
Pyruvate dehydrogenase (PDH) mitochondrial envelope oxidative decarboxylation of pyruvate (from cytoplasm) to form acetyl CoA, which thence feeds into tricarboxylic acid (Krebs) cycle
Sarcoplasmic reticulum ATPase (srATPase) SR membrane pumping of [Ca2+] back into SR after its electrically stimulated release
Succinate dehydrogenase (SDH) mitochondrial inner membrane oxidation of succinate to fumarate, in tricarboxylic acid (Krebs) cycle. Histochemical marker for aerobic capacity.

hexokinase

an enzyme that catalyzes the transfer of a high-energy phosphate group of ATP to a hexose sugar, usually d-glucose, producing d-glucose-6-phosphate.
References in periodicals archive ?
The actinide dependent hexokinase activity and actinide dependent ATP synthase activity were high but the blood ATP levels were low.
Like glucose, the 2-DG is taken up by cells via GLUTs and phosphorylated by hexokinase.
Membrane potential-dependent conformational changes in mitochondrially bound hexokinase of brain.
Increased Hexokinase Activity, of Either Ectopic or Endogenous Origin, Protects Renal Epithelial Cells against Acute Oxidant-induced Cell Death.
The expression of hexokinase II in clear-cell RCC is elevated.
Convergent evolution of similar enzymatic function on different protein folds: The hexokinase, ribokinase, and galactokinase families of sugar kinases.
It has been suggested that in tumours an increased ratio of hexokinase to glucose-6-phosphatase results in gradual accumulation of FDG and therefore in a further increase in SUV on delayed imaging.
226 was the one which correlated best with the hexokinase plasma reference method.
Activities of glucose and glycogen metabolizing enzymes: The activities of hexokinase and glucose6-phosphatase were determined by the methods described elsewhere (14), pyruvate kinase (15), glycogen phosphorylase (16), and fructosel, 6-bisphosphatase (17).
1) Physiologically, hemolysis can occur in several disease states such as glucose-6-phosphate dehydrogenase or hexokinase deficiency.