4.4 Cofactors, Coenzymes And Prosthetic Groups

Question 1

What is a cofactor?

Answer 1

A non protein helper component that helps enzymes carry out their function

Question 2

What is a coenzyme?

Answer 2

A cofactor that is an organic molecule

Question 3

How are inorganic cofactors obtained?

Answer 3

Via the diet as minerals

Question 4

Cofactor required for amylase

Answer 4

Cl- ion to catalyse breakdown of starch

Question 5

Prosthetic groups

Answer 5

Cofactors required by certain enzymes to carry out catalytic function - tightly bound and a permanent feature of the protein

Question 6

Examples of prosthetic groups

Answer 6

Zn2+ ions part of carbonic anhydrase, require for metabolism of CO2

Question 7

Precursor activation

Answer 7

Many enzymes are produced in an inactive form - inactive precursor enzymes
They need to undergo a change in shape (tertiary structure) to be activated
This can be done by addition of cofactors

Question 8

What is an apoenyzme and holoenzyme?

Answer 8

Precursor protein - apoenyzme

After cofactor is added - holoenzyme

Question 9

Other ways of activating precursor enzymes - what are these types called?

Answer 9

Action of another enzyme
Changes in certain conditions (eg temperature and pH)
They are called proenzymes or zymogens