The major classes of enzymes

Question 1

Oxidoreductases

Answer 1

• catalyze reactions in which one molecule is oxidized while the other is reduced, transfer of electrons (e-) and hydrogens H+
• oxidases, reductases, dehydrogenases, peroxidases

Question 2

Transferases

Answer 2

• transfer carbon, nitrogen or phosphate groups
• methyltransferases, aminotransferases, kinases, phosphorylases

Question 3

Hydrolases

Answer 3

• enzymes that catalyze a hydrolytic cleavage reaction ( transfer of functional groups to water)
• nucleases, proteases, phosphatases

Question 4

Lyases

Answer 4

• catalyze the cleavage of C-C, C-S, and C-N bonds, addition of groups to double bonds, or formation of double bonds by removal of groups.
• decarboxylases, aldolases, synthases

Question 5

Isomerases

Answer 5

• catalyze the rearrangement of bonds within a single molecule, transfer of groups within molecules to yield isomeric forms
• mutases, racemases

Question 6

Ligases

Answer 6

• Join two molecules in an energy-dependent process
• Formation of C-C, C-S, C-O, and C-N bonds by condensation actions coupled to cleavage (i.e., DNA ligase joins two DNA molecules).