Answer:
Substrate to the enzyme.
Explanation:
Enzymes are the bio catalyst that can increase the rate of the bio chemical reaction. Enzymes has the ability to work at the specific pH and temperature.
The enzymes follow the lock and key hypothesis. The substrate should fit into the active site of the enzyme as the key fits into its lock. The enzyme has high specificity for its substrate and should be structurally selective in nature.
Thus, the answer is substrate to the enzyme.
