The enzyme glucokinase is a
Six classes of enzymes:
a. Oxido-reductases — involved in oxidation and reduction of their substrates: - eg. Alcohol deHase.
Lactate deHase, xanthine oxidase, glutathione reductase, glucose-6-Po4-dHase
b. Transferases catalyze transfer of a particular group from one substrate to another eg. Aspartate and Alanine transaminase, Hexokinase phosphoglucomutase, hexose-1 -phosphate uridyl transferase, ornithine carbamoyl transferase.
Hexokinase and glucokinase → have same function in 1st step of glycolysis → form glucose — 6— phosphate from glucose, by phosphorylation.
i.e. transfers PO4 group from ATP to glucose.
i. Hexokinase present in all cells except liver and pancreas.
ii. Glucokinase →present in liver and Pancrease
c. Hydrolase brings about Hydrolysis → eg.
Glu-6-phosphatase, pepsin, trypsin, Esterases, Glycoside hydrolases, Lipase, Urease, Alkaline phosphatase
d. Lyases removal or addition of water, NH3, CO2 ie small molecules.
Eg. Fumarase, Arginosuccinase, histidine decarboxylase
e. Isomerase Isomerization, eg. UPP-glucoso isomerase, Epimerase, retinal isomerase, Racemase Triphosphate isomerase
f. 6. Ligases : involved in joining together two substrate. eg. Alanyl-t-RNA synthetase, glutamine synthetase, DNA ligases, succinate thiokinase.