Topic 3

Question 1

what are the factors affecting the activity of enzymes

Answer 1

• Temperature
• pH level
• Presence of activators or inhibitors

Question 2

How does temperature affect enzyme

Answer 2

• The rate of enzyme catalyses reaction increases with temperature only up to a point before the rate decreases which is called the optimal temperature
• When the temperature is below the optimal temperature, the hydrogen bonds and hydrophobic interactions that determine the shape of the enzyme are not flexible enough to cause induced fit when the substrate binds to its activation site for optimum catalysis
• When temperature is above the optimal temperature, the hydrogen bonds and hydrophobic interactions are too weak to hold the enzyme in its 3D configuration, causing protein denature of the enzyme
• Human enzymes’ optimal temperature ranges between 35 to 40 degrees celcius

Question 3

How does pH level affect enzyme activity

Answer 3

• When the concentration of H plus (pH level)changes, it shifts the balance of negative and positive amino acid residues on the enzyme
• This affects the ionic interactions that holds the enzyme in its 3D configuration
• affects the interaction between enzyme and substrate
• Most enzymes work in a range of 6 to 8
• enzyme Pepsin is able to digest protein in a pH level of 2

Question 4

Examples of enzymes

Answer 4

• Enzyme trypsin’s optimal temperature is 40 degrees celcius and works in a range of pH from 6 to 8
• Pepsin works in a acidic environment of the stomach (pH 2)

Question 5

How do Inhibitors and Activators affect enzyme activity

Answer 5

• Inhibitors are substances that binds to an enzyme to decrease its activity (inhibitor has similar shape to substrate that competes for the active site of enzyme - only applicable to competitive inhibitors)

Enzyme inhibitors work in two ways:
- (competitive inhibitors) compete with substrate for the same active site, occupying active site and preventing substrate from binding to the active site

• (non competitive inhibitors) bind to other locations of the enzyme other than the active site to change its configuration to an inactive configuration, preventing binding of substrate on the enzyme’s activation site

Example: Allosteric inhibitors (non competitive inhibitor) Binds at the allosteric site to change the configuration of the enzyme to reduce enzyme activity

Allosteric activator, binds to allosteric site to keep enzyme in its active configuration increasing enzyme activity