General Characterisitics of an Enzyme

1. Enzymes work very rapidly
•One molecule of enzyme can turn thousands or millions of substrate molecules into products per minute. For example, catalyse can transform approximately six million hydrogen peroxide molecules into oxygen and water molecules per minute.

2. Enzymes are not destroyed by the reactions which that catalyse
•Since enzymes are not altered by the reactions they catalysed, they can be used again. A small concentration of enzymes can bring about a large amount of biochemical reactions.

3. Enzyme-catalysed reactions are reversible
◦ lactose + water —lactase–> glucose + galactose
◦ lactose + water <–lactase— glucose + galactose
•The enzyme which catalyses a reaction works in such a way that the reaction can proceed from left to right or from right to left, depending on circumstances.

4. Enzymes are extremely specific
•Most enzymes are specific to one particular substrate molecule. Thus,  a given enzyme will catalyse only one reaction or one type of reaction. Maltase, for example, acts only on maltose.

5. Enzymes are denatured by high temperature
•An enzyme inactive at very low temperature. As temperature rises, its activity increases until the optimum temperature is reached. The optimum temperature is around 40′ C. Above the optimum temperature, the rate of reaction decline rapidly, ceasing altogether at about 60′ C. This is because enzymes are made of protein, so they are denatured at high temperature. When an enzyme becomes denatured, the bonds are broken and the polypeptide chains open up. The enzyme loses its normal shape and becomes inactive.

6. Enzymes are sensitive to pH
•Every enzymes has its own optimum pH in which it functions best. Small changes in the pH of the medium will denature the enzyme and render its activity. Alterations in the ionic charges of the acidic and basic groups of the enzyme change the shape of the enzyme.