An enzyme is denaturedwhen it loses its native conformation and its biological activity. 2. an enzyme is considered a catalystbecause it speeds up chemical reactions without being used up. 3. an enzyme is considered specificbecause of its ability to recognize the shape of a particular molecule. 4. a cofactor, such as a vitamin, binds to an enzyme and plays a role in catalysis. 5. when properly aligned, the enzyme and substrate form an enzyme-substrate (es) . 6. a substrate binds to an enzyme at the active site, where the reaction occurs. 7. in a catalyzed reaction a reactant is often called a substrate.