Classes of Enzymes

Question 1

Hydrolase

Answer 1

hydrolyzes chemical bonds

i.e. ATPases, proteases

Question 2

Isomerase

Answer 2

rearranged bonds within a molecule to form an isomer

Question 3

Ligase

Answer 3

forms a chemical bond

i.e. DNA ligase

Question 4

Lyase

Answer 4

breaks chemical bonds by means other than oxidation or hydrolysis
i.e. pyruvate decarboxylase

Question 5

Kinase

Answer 5

transfers a phosphate group to a molecule from a high energy carrier, such as ATP (phosphorylation) - can either activate or inactivate the enzyme
i.e. phosphofructokinase (PFK)

Question 6

Oxidoreductase

Answer 6

runs redox reactions

i.e. oxidases, reductases, dehydrogenases

Question 7

Polymerase

Answer 7

polymerase

i.e. addition of nucleotides to the leading strand of DNA by DNA polymerase II

Question 8

Phosphatase

Answer 8

removes a phosphate group from a molecule (reverses phosphorylation)

Question 9

Phosphorylase

Answer 9

transfers a phosphate group to a molecule from inorganic phosphate (phosphorylation) - can either activate or inactivate the enzyme
i.e. glycogen phosphorylase

Question 10

Protease

Answer 10

• protein-cleaving enzymes, hydrolyzes peptide bonds
  i. e. trypsin, chymotrypsin and pepsin

many enzymes are synthesized in inactive forms that are activated via cleavage by a protease

Question 11

chymotrypsin

Answer 11

cuts/cleaves on the carboxyl side of one of the large hydrophobic or aromatic residues
i.e. Tyr, Trp, Phe, Met and Leu*?

Question 12

trypsin

Answer 12

cleaves on the carboxyl side of positively charged basic residues
i.e. Arg, Lys