Investigating the Effect of Substrate Concentration on Catalase Reaction

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Investigating the Effect of Substrate Concentration on Catalase Reaction

Planning

-Aim:

The aim of the experiment is to examine how the concentration of the

substrate (Hydrogen Peroxide, H2O2) affects the rate of reaction of

the enzyme (Catalase).

-Background information:

Enzyme

Enzymes are protein molecules that act as the biological catalysts. A

catalyst is a molecule which can speed up chemical reaction but

remains unchanged at the end of the reaction. Enzymes catalyze most of

the metabolic reactions which take place within a living organism.

They speed up the metabolic reactions by lowering the amount of energy

needed to activate the reacting molecules. They are specific that

usually act on only one type of substrate, so each of them just

perform one particular reaction. Furthermore, only small amount of

enzyme is needed every time to speed up a reaction.

Enzymes are globular proteins that have a precise three-dimensional

shape. Their hydrophilic side-chains on the outside of the molecule

make them soluble in water.

Enzymes can catalyze both anabolic and catabolic reactions within an

organism. That means by the interaction between the side-chains of the

enzyme and the atoms of the substrate, the enzyme can encourage the

formation or breaking of bonds in a substrate molecule.

Each enzyme possesses an active site. The active site is a region of

enzyme which allows a substrate to bind with it. The configuration of

the active site gives the specificity of enzyme. That means the active

site and the substrate should be exactly complementary so that the

substrate can fit in perfectly. Once they collide, the substrate and

some of the side-chains of the enzyme’s amino acids form a temporary

bond so that the substrate can be held in the active site. They

combine to from an enzyme-substrate complex and the enzyme can start

its work. It is called the “lock and key” hypothesis. (Lock: enzyme,

key: substrate)

There is another hypothesis called “induced fit”. That is when the

substrate molecule combines with the enzyme it may induce a small

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