Enzymes

Question 1

What are enzymes?

Answer 1

Protein catalysts that control cellular metabolism. They reduce the activation energy required for a reaction. i.e. increase the rate of reactions.

Have substrates
Highly specific - only catalyse one reaction.

Question 2

Other uses of enzymes

Answer 2

Food production
Fermentation
Washing powder
Pharmaceutical targets
Pharmaceutical production

Question 3

What are substrates?

Answer 3

Chemicals that catalyse a reaction.

Question 4

Enzyme nomenclature

Answer 4

Enzymes are generally named for the substrate or chemical group they act on with the suffix “ase”

e.g. protein phosphatase, urease, etc.

Some enzymes retain older, trivial names e.g. trypsin, pepsin.

Question 5

Basic enzyme activity

Answer 5

Enzyme + substrate = ES = E + P

Question 6

Main types of enzyme

Answer 6

1. Oxidoreductases (mediate redox reactions)
2. Transferases (transfer groups from one molecule to another)
3. Hydrolases (Hydrolytic cleavage)
4. Lyases (Bond cleavage without hydrolysis)
5. Isomerases (structural alteration to a molecule)
6. Ligases (combine two molecules; ATP-dependent)

Question 7

What are active sites?

Answer 7

The active site is a 3D cleft with residues that have precise arrangement of residues to select target substrate(s)

Question 8

Lock and key theory

Answer 8

1890s

Rigid enzyme.

The active site fits the substrate perfectly.

Outdated concept.