Penicillin Flashcards
What does penicillin do?
inhibits bacterial growth and kills bacteria
What is the structure of penicillin?
Has a bicyclic structure with a 4-member B-lactam ring (cyclic amide) essential for the antibacterial activity of penicillin (broken ring, by acid or bacterial enzymes, penicillin no longer active)
5- member ring
How was penicillin modified to become more acid resistant to acid hydrolysis?
initial form, Penicillin G
side chain was modified to become more acid resistant (Penicillin V), resistant to breakdown by the patient, or breakdown by the bacteria
How does penicillin work?
antibiotics (penicillin) attacks cell well synthesis; humans do not have cell walls, little effect on humans but kills bacteria
beta-lactam antibiotics disrupts the formation of cell walls of bacteria but inhibits a key bacterial enzyme, transpeptidase
the high reactivity of the amide group in the ring causes it to irreversibly blind near the active site of transpeptidase as the ring breaks; inactivation of transpeptidase blocks the process of cell wall construction, prevents polypeptide cross-links from forming between the mucopeptide chains (without these links, cell wall is unable to support the bacterium, burst and dies)
How do strains (resistant to antibiotics) resist effects of penicillin?
strains produce penicillinase (a B-lactamase), which opens the B-lactam ring of the penicillin, making it inactive (Penicillin G can be inactivated by penicillinase)
Why is overprescribing an anti-biotic bad?
increased exposure of bacteria to the antibacterial agents, increased the number of resistant bacteria
