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)

Verified step by step guidance

1. Understand that enzymes have specific regions called active sites where substrates bind to undergo a chemical reaction.
2. Recognize that the binding of substrates to enzymes is typically reversible, allowing the enzyme to catalyze multiple reaction cycles.
3. Consider that some enzymes have active sites designed to accommodate more than one substrate simultaneously, especially in reactions involving multiple reactants.
4. Recall that the enzyme-substrate complex formation depends on the enzyme's active-site architecture and the specific reaction mechanism it facilitates.
5. Conclude that the most accurate statement is that an enzyme may bind one or more substrates simultaneously, depending on its active-site structure and reaction mechanism.