CPAC 01- enzyme initial rate of reaction

Question 1

What are the 4 factors affecting enzyme activity?

Answer 1

• enzyme conc
• substrate conc
• pH
• temperature

Question 2

How do you set up a control for this experiment?

Answer 2

add 2cm3 trypsin to 2cm3 of distilled water and use this as a reference cuvette

Question 3

How can a colorimeter determine the rate of reaction of trypsin and milk?

Answer 3

• as trypsin digests proteins in milk (casein), it becomes more translucent so more light passes through
• the decrease in absorbance can be measured by the colorimeter

Question 4

Outline the method used to measure the effect of enzyme concentration on enzyme activity, using trypsin and milk

Answer 4

1. Dilute stock solutions of trypsin with distilled water to produce 4 concentrations (0.2%, 0.4%, 0.6%, 0.8%)
2. Zero the colorimeter using 2cm3 of milk solution and 2cm3 of distilled water
3. To another cuvette, add 2cm3 of milk suspension and 2cm3 of trypsin solution. mix, place in colorimeter and measure absorbance every 15 seconds for 5 minutes
4. Rinse cuvette with distilled water
5. Repeat step 3 at all concentrations

Question 5

How is the rate of reaction calculated using time?

Answer 5

1/time

Question 6

Why is the initial rate used?

Answer 6

initial rate is the only point during the reaction when concentration of products and reactants is known because the rate of an enzyme-controlled reaction is high so concentrations of reactants changes rapidly