enzyme classes

Question 1

oxidoreductases

Answer 1

to catalyse oxidation/reduction reactions, transfer of O and H atoms or electrons from one substance to another.

recognition: NAD –> NADH
FAD –> FADH

Oxidoreductases uses riboflavin - vitamin B2 and Niacin - vitamin B3 as cofactors.

examples: dehydrogenase, oxidase, reductase, oxygenase

Question 2

transferases

Answer 2

transfer of a functional group from one substance to another.

recognition –> exchange of functional group

transferase use pyridoxine - vitamin B6 as cofactors.

the group may be methyl-, acyl, amino or phosphate group.

example: kinase, phosphorylase, aminotransferase

Question 3

hydrolases

Answer 3

formation of 2 product from one substance by hydrolysis + addition of H20

recognition water is used. break bonds + add water.

example:
endo/exo nuclease
endo/exo peptidase
glycosylase
lipase
phosphatase
esterase
phosphodiesterase
phosphodipase
protease

Question 4

lyases

Answer 4

• non-hydrolytic (without water)
  addition or removal of groups from substrates

c-c
c-n
c-s
c-0 bonds may be cleaved

example: synthase, decarboxylase, aldolase

Question 5

isomerase

Answer 5

• intramolecular rearrangement = changes within a single molecule
• recognition –> same sumformula but different structure

ex: mutase, epimerase, racemases