Which enzyme produced by bacteria helps them resist penicillin by breaking down the drug?

Which enzyme produced by bacteria helps them resist penicillin by breaking down the drug?

• A. Beta-lactamase
• B. Amylase
• C. Lipase
• D. Protease

Answer: (A)

Bacteria resist penicillin by producing beta-lactamase, an enzyme that hydrolyzes the beta-lactam ring in penicillin. That ring is essential for the antibiotic to bind penicillin-binding proteins and inhibit cell wall synthesis; once the ring is opened, penicillin can no longer inactivate its targets, so the drug is ineffective. Other enzymes listed—amylase, lipase, and protease—act on starch, fats, and proteins, respectively, and do not modify penicillin, so they don’t confer resistance to this antibiotic.

Bacteria resist penicillin by producing beta-lactamase, an enzyme that hydrolyzes the beta-lactam ring in penicillin. That ring is essential for the antibiotic to bind penicillin-binding proteins and inhibit cell wall synthesis; once the ring is opened, penicillin can no longer inactivate its targets, so the drug is ineffective. Other enzymes listed—amylase, lipase, and protease—act on starch, fats, and proteins, respectively, and do not modify penicillin, so they don’t confer resistance to this antibiotic.