Enzyme inhibition decreases the ability of an enzyme to catalyze a reaction. There are several forms of enzyme inhibition . Choose the type of inhibition involved in this example : Sulfanilamide binds to the active site of a bacterial enzyme , dihydropteroate synthase , that normally reacts with p-aminobenzoate ion to form dihydrofolic acid. This antibacterial agent prevents the production of folic acid which is needed for bacterial DNA and selectively kills the bacteria .