Zymogen or proenzyme is a :

A zymogen, also known as a proenzyme, is an inactive precursor of an enzyme. It is synthesized and secreted in this inactive form by the cell. The zymogen requires a biochemical change to become an active enzyme. This change usually involves the cleavage of a peptide bond by a protease, which results in a conformational change in the protein structure of the zymogen. This conformational change activates the enzyme, allowing it to perform its catalytic function. This mechanism of activation ensures that the enzyme is only active in specific locations or under specific conditions, preventing unwanted or harmful enzymatic activity.