Measuring Enzyme Activity
- The progress of enzyme-catalysed reactions can be investigated by:
- Measuring the rate of formation of a product using catalase
- Measuring the rate of disappearance of a substrate using amylase
Investigating catalase activity
- In this investigation, the rate of product formation is used to measure the rate of an enzyme-controlled reaction:
- Hydrogen peroxide is a common but toxic by-product of metabolism
- This means it must be broken down quickly
- Catalase is an enzyme found in the cells of most organisms that breaks hydrogen peroxide down into water and oxygen
- Hydrogen peroxide and catalase are combined and the volume of oxygen generated is measured in a set time
- The rate of reaction can then be calculated
Investigating Catalase Diagram
Experimental set-up for investigating the rate of formation of a product using catalase
Investigating amylase activity
- In this investigation, the rate of substrate disappearance is used to compare rates of reaction under different conditions:
- Amylase is a digestive enzyme that hydrolyses starch into maltose and glucose
- Amylase functions best at pH 7 and 37oC (all enzymes operate best under specific optimal conditions)
- Amylase and starch are combined and this reaction mixture is then tested for starch at regular time intervals
- This can be done by taking samples from the reaction mixture at each time interval and adding each sample to someĀ iodine solution (starch forms a blue-black colour with this solution)
- In this way, the time taken for starch to be broken down can be measured
- The investigation can be repeated under a variety of conditions (e.g. by altering pH or temperature) and the reaction rates can then be compared
Investigating Amylase Reaction
Experimental set-up for investigating the rate of disappearance of a substrate using amylase