Regarding the enzyme-substrate complex, which statement is most accurate about how enzymes bind reactants?

• A. Enzymes bind substrates only after products have been released from the active site.
• B. An enzyme may bind one or more substrates simultaneously, depending on its active-site architecture and reaction mechanism.
• C. An enzyme binds substrates irreversibly, so it can catalyze only a single turnover.
• D. An enzyme can only bind one reactant at a time.

Answer: (B)