Enzyme Properties

Question 1

Define an enzyme

Answer 1

Biological catalyst - increases rate of reaction without altering final equilibrium

Question 2

Effect of enzyme on activation energy

Answer 2

Substrate has higher affinity to active site than product.

As product increases - more inhibition.

Question 3

Substrate specificity

Answer 3

Enzymes catalyse only one reaction.

Enzymes are stereospecific.

Question 4

6 Types of enzyme classification

Answer 4

Oxidoreductase - add )2 or remove 2H in reduction reaction.
Transferase - transfers functional groups
Lyases - add groups to C=C bonds. Catalyses cleavage of C-C, C-O and C-N bonds.
Hydrolases - hydrolysis reactions.
Isomerases - Isomerisation reactions
Ligases - form C-C or C-N bonds with ATP cleavage.

Question 5

Lock and key model

Answer 5

• Every enzyme has specific active site

- Subrate is complementary to active site

Question 6

Induced fit Model

Answer 6

Partial recognition causes conformational change so enzyme locks onto substrate enabling reaction to occur

Question 7

Mechanism of Chymotrypsin reaction

Answer 7

1. Enzyme creates nucleophile from serine side chain.
   Nucleophile attacks the substrate.
   Covalent intermediate is formed bonded to the serine and the first product is produced
2. Enzyme creates a nucleophile from water (OH-).
   OH- attacks covalent intermediate, breaking ovalent bond with serine.
   Second product released.