Explain how changing the pH and/or salt concentration of a solution containing an enzyme can destroy the.....?

Question

enzyme activity

Answer 1

Each enzyme has an optimal pH at which it is most active - rate of reaction is at its highest at this point. Extremes of pH can lead to enzyme denaturation, because the structure of the catalytically active protein molecule (i.e. the enzyme) depends on the ionic character of the amino acid side chains. Excess [H+] or [OH-] ions may disrupt ionic bonds.

Also ionization of the active site may occur. The catalytic process usually requires the enzyme or the substrate to have specific chemical groups in order to react. However at a non-optimum pH, these chemical groups get deprotonated/protonated and hence is unable to react.

Hope I've helped

Answer 2

Most enzymes have a narrow pH optimum (papain is an exception). pH affects the ionization of each amino acid residue in the protein, and therefore change the tertiary and quaternary structures of the protein molecule, and thus the structure of the active site.  Salt has effect on the solubility of the protein. This is called salting-in and salting-out. Some salt is required to dissolve the protein. Too high a salt concentration causes the protein to come out of the solution. That is how we use sodium sulphate to fractionate proteins.