Enzyme theory: explore the properties and functions of enzymes

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Introduction

In this experiment I will attempt to investigate how the change in temperature effects the catalyse reaction and what the optimum temperature is.

Key factors


Scientific knowledge

Enzymes:

Because enzymes are proteins they can be destroyed at high temperatures, this is called denaturing. Enzymes are used to catalyse (speed up) chemical reactions. There are many types of enzymes and they are all used to break down certain food molecules, this is described in the lock and key theory and the induced fit theory.

Enzyme theory:

Lock and key theory.

        Enzymes are biological catalysts. The lock and key theory was suggested in 1894 by Emil Fischer and properly described as follows "The specificity of an enzyme (the lock) for its substrate (the key) arises from their geometrically complementary shapes".

        The lock and key theory is simply a way of describing how specific an enzyme is for its substrate. Just like a lock requires a specifically shaped key for it to work so does an enzyme. Each enzyme is a protein which is a polypeptide chain folded into a complex 3 dimensional structure. Part of that structure contains the active site which is where the enzyme can bind to the substrate on which it will perform some chemical reaction. Because each enzyme performs a specific task on a specific substrate the active centre of the enzyme can be considered to be the "lock" which requires the specific "key" or substrate to perform the function. Smaller keys, larger keys, or incorrectly positioned teeth on keys (incorrectly shaped or sized substrate molecules) do not fit into the lock (enzyme). Only the correctly shaped key (substrate) opens a particular lock. If we imagine the enzyme as the lock and the substrate the key - the key is inserted in the lock and if this is his right enzyme for the substrate the lock is turned, and the door is opened and the reaction proceeds.

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        The active site is the specific region of the enzyme which combines with the substrate. The products are released from the enzyme surface to regenerate the enzyme for another reaction cycle.

        The active site has a unique geometric shape that is complementary to the geometric shape of a substrate molecule. This means that enzymes specifically react with only one or a very few similar compounds.

        

Induced Fit Theory:

This theory uses instead of the analogy the key in the lock but instead the glove in the hand this theory also explains that a protein is flexible. Enzymes act as ...

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