The aim of this investigation is to see the impact that temperature has on an enzyme and substrate.

Introduction

Enzymes are referred to as catalysts. A catalyst is something that speeds up the rate of chemical reaction. Enzymes are known to speed up the rate of formation of a product by a factor of at least one million. In a biological system, the rate of reaction may occur very slowly, or in some cases not at all. This is due to the absence of an enzyme. Most enzymes tend to be large protein molecules, with a three a dimensional shape.

Unlike chemical catalysts like manganese dioxide, enzymes are specific. The meaning to that is that, each enzyme will normally catalyse only one reaction. In order for the enzyme to catalyse it must join the substrate. The substrate is the part which combines with the enzyme at its active site. Enzymes tend to be larger than their substrate, and the active site of an enzyme is relatively small part. It consists of 3 - 12 amino residues; the rest of the enzyme molecule is involved in maintaining the shape of the active site. The shape of the active site is essential because it is complementary to the shape of the substrate molecule. When the active site and substrate interlink, it is known as the ‘lock and key theory’. In simple terms the ‘lock and key theory’ says that like each lock has a specific key to unlock it, the same would theoretically apply to the enzyme’s active site and substrate, when forming a temporary enzyme-substrate complex. Once the substrate joins the active site, it is common for the active site to change shape. The process is known as induced fit. As mentioned earlier, once the substrate and active site join together, they form an enzyme-substrate complex.

When a chemical reaction occurs, there can be two possible out comes. One an exergonic (exothermic) reaction where heat is given out, or two an endergonic (endothermic) reaction when heat is taken in. In most reactions, it is likely to be to an exothermic reaction rather than an endothermic reaction. In living cells it is important to remember that in order for a chemical reaction to take place you have to input some source of energy. This is referred to as the activation energy (Æ).

As enzymes are proteins, they are sensitive to change in their environment. Changes in temperature ...