Question

From the given graph, find out which of the following factors affect the enzyme activity?

(i) Temperature
(ii) Substrate concentration
(iii) pH
(iv) Competitive inhibitor

• A. (i) and (ii)
• B. None of these
• C. (i) and (iii)
• D. (iii) and (iv)

Answer 1

Answer: (C)

Almost all enzymes consist of proteins. Enzymes catalyze the biological reactions without themselves being used up. Enzymes cannot be transported from cell to cell, so each enzyme is synthesized in a particular living cell.
An enzyme molecule combines with a substrate (S) to form an enzyme-substrate complex. This state is known as the transition state. During the conversion of substrate to product, the transition states formed are temporary and unstable. The enzymatic reaction reduces the activation energy. A non-catalyzed reaction requires higher activation energy than that for a catalyzed reaction. However, there is no difference between the free energies in catalyzed and non-catalyzed reactions. The active site is represented by a crevice or pocket. The enzyme reacts with the substrate only at these active sites.
The conditions that can change the tertiary structure of protein affect the activity of the enzyme. Normally, enzymes are functional in a range of temperature. At low temperature, enzymes become temporarily inactive, while at a high temperature they become denatured. Therefore, each and every enzyme have an optimum temperature at which its activity becomes maximum.
Likewise, normally, enzymes remain active at a very narrow range of pH. The pH at which an enzyme exhibits maximum activity is known as the optimum pH. Below and above this pH, the enzymatic activity decreases.