What is the part of an enzyme that binds with the substrate called?

• A. Active site
• B. Enzyme site
• C. Substrate binding site
• D. Catalytic site

Answer: (A)

The main idea here is that enzymes have a specific region that recognizes and binds their substrate. This region is called the active site. The active site has a shape and chemistry that fit the substrate like a key fits a lock, so the substrate binds there to form the enzyme-substrate complex. Binding occurs through non-covalent interactions, and this binding often induces a slight change in the enzyme's shape to place reactive groups in the right positions to start the chemical reaction. This arrangement also helps lower the activation energy, making the reaction proceed faster.

While the phrase “substrate binding site” describes what happens, the standard term for this region is the active site. The idea of a “catalytic site” can refer to where the chemistry happens, not just where binding occurs, so it’s not the best label for the part that binds the substrate. And “enzyme site” isn’t a conventional term.