Antibiotics like penicillin are often called “magic bullets” because they target structures unique to bacteria, such as the peptidoglycan layer in their cell walls. These antibiotics block the enzymes responsible for forming peptide cross-links in peptidoglycans, weakening the bacterial wall and ultimately killing the bacteria.
Penicillins and their synthetic derivatives contain a special structure called the beta-lactam ring, which is key to their effectiveness. Beta-lactam antibiotics have several important advantages:
- They target pathways that exist in bacteria but not in human cells.
- They stay in the body long enough to be clinically useful.
- They reach effective concentrations in most tissues and organs.
- They work against a wide variety of bacterial species.
These antibiotics act by mimicking the natural substrate of transpeptidase enzymes, which bacteria use to build strong cell walls. When penicillin binds to these enzymes, it activates the drug, which in turn inactivates the enzyme—preventing the bacteria from forming proper cell walls.
However, the widespread use of antibiotics has led to the rise of antibiotic-resistant bacteria. The most common resistance mechanism involves the production of beta-lactamase enzymes by bacteria. These enzymes act like a “bulletproof vest”, protecting bacteria by breaking open the beta-lactam ring and deactivating the antibiotic.
Beta-lactamases work by forming a temporary bond with the antibiotic, hydrolyzing it, and then returning to their active form—ready to destroy more antibiotic molecules.
This evolution of resistance is a major public health concern, making it harder to treat once-curable infections and emphasizing the need for responsible antibiotic use and continued research.
Name: Yashashvi Kumar
Department: Zoology NEET
Narayana Jaipur Center (NIHQ)