Common types of Enzymes

Question 1

Kinase (K)

Answer 1

Catalyses the phosphoryl transfer from one molecule (usually ATP) to another

Glucose + ATP -> Glucose-6-Phosphate + ADP

Question 2

Phosphorylase (P’Lase)

Answer 2

Catalyses the covalent addition of inorganic phosphate (Pi) to a molecule

Eg. Glycogen Phosphorylase

Question 3

Phosphotase (P’Tase)

Answer 3

Catalyses the cleavage of a phosphate to yield the dephosphorylated product and Pi

Eg. Glucose-6-phosphatase

Question 4

Dehydrogenase (DH)

Answer 4

Catalyses an oxidation/reduction reaction commonly using NADH/NAD+, NADPH/NADP+ or FADH2/FAD as cofactors

Eg. Glyceraldehyde-3-phosphate dehydrogenase

Question 5

Mutase (M)

Answer 5

Catalyses the shift of a phosphoryl group from one atom to another within the same molecule

Eg. Phosphoglycerate mutase

Question 6

Isomerase (I)

Answer 6

Catalyses the conversion of one isomer to another

Eg. Triose Phosphate Isomerase

Question 7

Hydratase

Answer 7

Catalyses the addition/removal of water

Eg. Enolase

• Is a dimeric glycolytic enzyme that catalyses the conversion of 2-phosphoglycerate to phosphoenolpyruvate. The active site contains 2 Mg2+ cofactors and 5 highly conserved residues (His159, Glu168, Lys345 and Lys396) that are critical for catalysis

Question 8

Synthase

Synonymous terms: synthase/synthetase/ligase

Answer 8

Catalyses the synthesis of a product

Eg. Citrate synthase
This catalyses the addition of an acetyl group from Acetyl-CoA to oxaloacetate to form citrate in the first step of the Krebs cycle. The hydrolysis of the thioester bond in Acetyl-CoA make the reaction highly exergonic.