1 ) 

A bacterial protease that is secreted from a disease-causing bacterium could act as an antigen and cause the production of an antibody.

2 ) 

Bacterial proteases are important in the nitrogen cycle as they are able to catalyse the breakdown of the organic nitrogen molecules nucleotides and urea.

3 ) 

Non-competitive inhibition of a protease that has an optimum pH of pH2 can be overcome by increasing the substrate concentration and increasing the pH.

4 ) 

Water molecules are required when peptide bonds that link the monomers together are broken by the action of proteases in condensation reactions.