Question

1-What are the factors that affect enzyme activity?

2-How the present of denaturation affecting enzyme activity?

3-Explain how the excess of H₂O₂inhibit the enzyme?

Answer 1

1. Factors affecting enzyme activity are temperature, pH, concentration of enzyme and concentration of substrate and presence of inhibitors.

All the enzymes work at a given temperature and given pH called as optimum temperature and optimum pH. At this temperature and pH the rate of enzyme catalysed reaction is the maximum and any increase or decrease in this optimum value results in the decrease of the rate of reaction.

The rate of an enzyme catalyzed reaction increases whenever the number of enzyme molecules are increased. But this is up to a certain limit after which the rate becomes constant because the number of substrate molecules become limiting. Similarly whenever the substrate concentration is increased, the rate of reaction increases initially but after due to the limitation of enzyme molecules, the rate becomes constant.

Whenever an inhibitor is present in a reaction medium, then it will either bind to the active site of the enzyme where a substrate bind or it will modify the shape of the active site in such a way that substrate will not be able to bind and this will prevent the enzyme from catalysing the reaction, thereby decreasing the rate of reaction.

2. Denaturation is the process of unfolding of enzyme either at high temperature or due to the presence of denaturing agents like urea. This leads to unfolding of three dimensional structure of enzyme and therefore complete loss of its structure making the enzyme unable to catalize the reaction. Therefore we can say that the activity of enzyme is dependent upon its structure and when the structure is lost, the activity is also lost.

3. Excess of peroxide in a reaction medium leads to the oxidation of enzyme. Degradation of hydrogen peroxide leads to the formation of Oxygen and other reactive oxygen species which react with enzyme and destroy the bonding present between amino acid side Chains of the enzyme. This results in disruption of the structure of enzyme and therefore loss of its catalytic activity.

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