Question

Which of the following would normally alter the affinity of an enzyme for its substrate? Select all that apply.

answer choices

a.pH

b.Temperature

c.Ionic concentrations

d.Enzyme concentration

Answer 1

A, B, C

Enzymes are protein molecules that speed up the rate of a biological reaction. They are very specific for their substrate. All the enzymes work at a specific range of temperature and pH called as optimum temperature and optimum pH. Any deviation in this optimum range is detrimental to the structure of enzyme and therefore results in the loss of its catalytic activity.

Effect of temperature on enzyme activity

When the temperature is decreased from the optimum temperature, it results in inactivation of the enzyme, although the structure of enzyme remains intact.

When the temperature is increased beyond the optimum temperature, it results in denaturation of enzymes. It is because the chemical bonds present between various amino acid side Chains of an enzyme are disrupted at Higher temperature which leads to unfolding of enzyme. This results in loss of the native structure of enzyme and therefore a complete loss of its activity. However if the temperature is decreased again to the optimum temperature, then the chemical bonds are reformed and the catalytic activity is regained. During the denaturation process all the bonds accept peptide bonds are broken. This keeps the primary structure intact due to which the enzyme renatures again.

Effect of pH on enzyme activity

When the pH is decreased, hydrogen ion concentration in the solution gets increased. These positively charged ions interact with negatively charged side chain of amino acid altering the bonding pattern between amino acids. This leads to alteration of enzyme structure and therefore loss of its catalytic activity.

When the pH is increased, hydroxyl Ion concentration in the solution gets increased. These negatively charged ions interact with the positively charged side chain of amino acid altering the bonding pattern between amino acids. This results in loss of enzyme structure and therefore loss of its catalytic activity.

Requirement of ionic cofactor -

Not all enzymes work alone. Some of the enzymes require and additional charge molecule which is called as an ionic cofactor. These cofactor do not increase or decrease the rate of the enzymatic reaction but are required for the proper functioning of the enzyme.

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