Plant Hexokinase

In most animal, plant, and microbial cells, the enzyme that phosphorylates glucose is hexokinase. Magnesium ion (Mg ) is required for this reaction, as for the other kinase enzymes in the glycolytic pathway. The true substrate for the hexokinase reaction is MgATP. The apparent K , for glucose of the animal... 

The role of L-glycerose as a precursor of l sugars is doubtful, since it inhibits glycolysis in plants and animals, probably by the formation of L-sorbose 1-phosphate, which inhibits hexokinase.74-75... 

Hexokinase is of great biological interest since it would appear that not only in yeast cells but in most, if not all, plant and animal cells phosphorylation at C6 of the common hexoses D-glucose, D-fructose and D-mannose initiates sugar utilization. Since on solution in water the crystalline hexoses quickly undergo mutarotation, resulting in an equilibrium mixture of various tautomeric modifications, the fermentability... 

Specific activation or inhibition Transport of glucose can be increased or decreased by specihc compounds insulin increases the transport whereas phloridzin, a plant glycoside, inhibits glucose transport by muscle. Insulin increases glucokinase activity in liver, whereas a plant sugar, mannoheptulose, inhibits glucokinase activity. Hexokinase is inhibited by its product, glucose 6-phosphate. 

Xiao WY, Sheen J, Jang JC. 2000. The role of hexokinase in plant sugar signal transduction and growth and development. Plant Mol Biol 44 451-461. 

Hexokinase occurs in a wide variety of animals, plants and microorganisms. It is an example of the induced-fit model of substrate binding (S tion 5.2) in which glucose induces significant alterations in the tertiary structure of the enzyme. The positional changes of the amino acid residues within the... 

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