Enzymes are proteins. Proteins are long chains of amino acids linked to each other by peptide bonds. Amino acids have many functional groups in their structure.

These functional groups are many of them at least, ionisable. As they are weak acids and bases in chemical nature, this ionisation is influenced by pH of the solution. For many enzymes activity is influenced by surrounding pH. This is depicted in the curve below, explain briefly.

Explanation

Enzymes, generally function in a narrow range of pH. Each enzyme shows its highest activity at a particular pH called optimum pH. Activity declines both below and above the optimum value given graph depicts enzyme activity at maximum range.