Page 77 - Biochemistry2 (08PB403)

Compare Glucokinase & Hexokinase

Glucokinase Hexokinase

Site Liver only All tissue cells
Affinity to
glucose Low affinity (high Km) (it acts only in High affinity (low Km) (it acts
presence of high blood glucose even in presence of low blood
Substrate concentration)
glucose concentration)
Effect on
insulin Glucose only Glucose, Fructose, Galactose
Effect of
glucose -6 Induce synthesis of glucokinase No effect
Phosphate
Function No effect Allosterically inhibits hexokinase

Acts on liver after meals. It removes It phosphorylates glucose inside
glucose coming in portal circulation, the body cells, this makes
converting it into glucose-6-
phosphate glucose concentration in blood
more than inside the cells. This

leads to continous supply of
glucose for the tissues even in

the presence of low blood
glucose levels

76