Vernier Software & Technology

# Testing Enzyme Activity (Spectrometer)

## Introduction

Enzymes are molecules that regulate the chemical reactions that occur sin all living organisms. Almost all enzymes are globular proteins that act as catalysts, substances that speed up chemical reactions. Enzymes catalyze reactions by reducing the activation energy for a specific reaction to occur and yet are neither destroyed nor altered during this process. At the molecular level, enzymes catalyze these reactions by briefly binding to the substrate or reactants to form an enzyme-substrate complex. The reaction takes place while the substrate is bound to the enzyme, converting the substrate to the new product. The new product is then released from the enzyme substrate complex and the enzyme is then free to bind with more substrate.

${\text{Enzyme}} + {{\text{Substrate}}} \to {{\text{Enzyme-Substrate Complex}}} \to {\text{Enzyme}} + {{\text{Product}}}$

H2O2 is toxic to most living organisms. Many organisms are capable of enzymatically destroying the H2O2 before it can do much damage. H2O2 can be converted to oxygen and water as follows:

${\text{2}}\ {\text{H}}_{\text{2}}{\text{O}}_{\text{2}}{\text{(aq)}} \to {\text{2}}\ {\text{H}}_{\text{2}}{\text{O}} + {\text{O}}_{\text{2}}{\text{(g)}}$

Although this reaction occurs spontaneously, enzymes increase the rate considerably. At least two different enzymes are known to catalyze this reaction: catalase, found in animals and protists, and peroxidase, found in plants. A great deal can be learned about enzymes by studying the rates of enzyme-catalyzed reactions.

In this Preliminary Activity, you will use a colorimetric assay to determine the rate of reaction of the enzyme peroxidase.

After completing the Preliminary Activity, you will use reference sources to find out more about enzymes, turnips, and peroxidase, and then you will choose and investigate a researchable question. Some topics to consider in your reference search include the following:

• catalyst
• enzyme
• substrate
• peroxidase
• proteins
• denature
• Michaelis-Menten constant
• Lineweaver-Burk plot

## Objectives

• Identify variables, design and perform the investigation, collect data, analyze data, draw a conclusion, and formulate a knowledge claim based on evidence from the investigation.
• Determine the rate of the peroxidase catalyzed reaction converting H2O2 to H2O and O2.
• Gain increased understanding of factors affecting peroxidase activity.

## Sensors and Equipment

This investigation features the following Vernier sensors and equipment.

You may also need an interface and software for data collection. What do I need for data collection?

## Investigating Biology through Inquiry

See other experiments from the lab book.

 1 Buffer Investigations 2 Diffusion 3 Investigating Osmosis 4 Chemistry of Membranes 5 Investigating Protein 6A Testing Catalase Activity (O2 Gas Sensor) 6B Testing Catalase Activity (Gas Pressure) 6C Testing Enzyme Activity (Spectrometer) 7 Introduction to Biofuels: Enzyme Action 8 Analysis of Enzymes using Tyrosinase 9 Cellular Respiration 10A Sugar Metabolism with Yeast (Carbon Dioxide Gas) 10B Sugar Metabolism with Yeast (Ethanol) 11 Fermentation with Yeast 12 Photosynthesis by Chloroplasts 13 Transpiration of Plants 14 Plant Pigments 15 Heart Rate 16 Investigating Dissolved Oxygen 17 Investigating Primary Productivity 18 Modeling Population Dynamics 19 Water Monitoring 20 Evolution of Cellobiase in Fungi 21 Introduction to Molecular Evolution 22 Evolution of Yeast

### Investigation 6C from Investigating Biology through Inquiry Lab Book

#### Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.