Which action must occur for an enzyme to catalyze a chemical reaction?

correct substrate to bind the active site of the enzyme.

Explanation:

For an enzyme to catalyze a chemical reaction it is very essential for the correct substrate to bind the active site of the enzyme.

The Active site consists of two parts

1. Binding site

2. Catalytic site

The binding site consists of amino acid residues that bind to the correct substrate while the catalytic site has the amino acids that lead to the catalysis.

The active site's shape is such that only the right substratum easily binds to it and thus the catalytic reaction occurs.