Catalase Investigation

Catalase Investigation

Introduction

This investigation aims to determine the effect that varying the pH of

the conditions in which a reaction between an enzyme and a substrate

takes place. In particular the reaction of hydrogen peroxide being

broken down into water and oxygen by an enzyme, catalase.

2H2O2 à2H2O + O2

This reaction would normally occur naturally, but in the presence of

the enzyme catalase the reaction occurs much more rapidly and

vigorously.

Enzymes

An enzyme is a biological catalyst. A catalyst can be defined as; a

substance that increases the rate of a chemical reaction by reducing

the activation energy, but which is left unchanged by the reaction.

There are more than 1500 known enzymes today, each one specific to its

substrate. An enzyme is any one of many specialised organic

substances, composed of polymers of amino acids, which act as

catalysts to regulate the speed of the many chemical reactions

involved in the metabolism of living organisms.

There are 6 major classes of enzymes:

1. Oxidoreductases which are involved in oxidation, reduction, and

electron or proton transfer reactions;

2. Transferases, catalysing reactions in which groups are

transferred;

3. Hydrolases which cleave various covalent bonds by hydrolysis;

4. Lyases catalyse reactions forming or breaking double bonds;

5. Isomerases catalyse isomerisation reactions;

6. Ligases join substituents together covalently.

However, how they are classed depends on what kind of reaction they

control. Many other enzymes control many other different kinds of

reactions.

Most enzymes are named by adding "ase" on the end of the substrate

which they break down. For example enzymes specific to protein are

called "proteases", similarly the enzyme that controls urea

decomposition is called "urease". However, some enzymes retain their

names from before this method of naming came into use. Amylase, the

enzyme that breaks down starch, is a good example of this, as are