III produce an enzyme that blocks the action of beta lactam antibiotics in periplasmic space. Which arrow in the structural diagram of Penicillin G denotes the site of action of this enzyme?
Ans: B. B
(Ref: Goodman p1478; Katzung 13/e p770, KDT p /6, 6/c p694)
- An amide bond.
- Found in Penicillin G structure is represented by ‘B’.
Beta lactam ring:
- Fused to five-membered thiazolidine ring.
- Fusion causes β-lactam ring to be more reactive (than monocyclic β-lactams).
- Two fused rings distort β -lactam amide bond à Removes resonance stabilization normally found in these chemical bonds.