Biology – Factors that affect enzyme action | e-Consult

Experimental Procedure:

• Enzyme Solution Preparation: Prepare a series of enzyme solutions with varying concentrations. Ensure the substrate concentration remains constant across all trials.
• Reaction Setup: Mix the enzyme solution with the substrate solution in a controlled volume of buffer solution.
• Rate Measurement: Measure the rate of reaction by monitoring the production of a product (e.g., oxygen gas) over a fixed period. This can be done using a gas sensor or by measuring the volume of liquid displaced. Alternatively, measure the disappearance of the substrate using spectrophotometry.
• Replicates: Perform multiple replicates (at least three) at each enzyme concentration.
• Control: Include a control experiment with only the substrate and buffer to account for any background reaction.
• Variable Control: Maintain constant temperature, pH, and substrate concentration across all trials. Ensure adequate mixing.

Relationship between Enzyme Concentration and Reaction Rate:

The rate of an enzyme-catalysed reaction is directly proportional to the enzyme concentration, provided that the substrate concentration is not limiting. This is because the reaction rate depends on the number of enzyme molecules available to bind to the substrate and catalyze the reaction. Increasing the enzyme concentration increases the probability of substrate binding and, therefore, increases the rate of product formation. However, at very high enzyme concentrations, the reaction rate may plateau because all the substrate molecules are already bound to enzyme molecules, and adding more enzyme will not increase the rate further. This is because the enzyme is saturated with substrate.