Chem Basis - Penicillins 1

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Chem Basis - Penicillins 1
2014-01-21 14:34:59
Chem Basis Penicillins
Chem Basis - Penicillins 1
Chem Basis - Penicillins 1
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  1. Modifications of the naturally occurring penicillin compounds altered what characteristics of B-lactam antibiotics?
    Spectrum of activity, Stability against beta-lactamases and acid, gastrointestinal absorption, side effects/adverse effects, DDIs and protein binding
  2. All penicillins are bactericidal or bacteriostatic, and why?
    Bacteriocidal, b/c inhibit bacterial cell wall synthesis
  3. (True/False) The mechanism of inhibition of cell wall synthesis involves binding to Penicillin Binding Proteins (PBP's) in the bacterial cell membrane and inhibiting the enzyme D-Alanine-transpeptidase in the bacterial cell membrane.
    False, Should say “Cell Wall”
  4. What is the name for the enzyme that cross-links the peptidoglycan molecules in the bacterial cell wall?
  5. The enzyme anchors to cell wall via a nucleophilic attack on a glutamate residue on the cell wall. Penicillins act as false alanine residue substrate for D-Alanine-transpeptidase and can acylate the transpeptidase nucleophile resulting in inactivation.
    False, should say glutamate residue
  6. When D-Alanine-transpeptidase mistakes a penicillin for a glutamate residue it becomes acylated resulting in inactivation. Through this process, what type of bond forms between the penicillin and the enzyme?
  7. (True/False) Penicillins bind to and inhibit D-alanine-transpeptidase.
  8. (True/False) Penicillins prevent the cross linking of two peptidoglycan molecules which result in inhibition of cell wall synthesis.
  9. (True/False) Penicillin inhibition of cell wall synthesis involves nucleophilic attack by the PBP on the beta lactam ring.
  10. (True/False) Penicillins form an ion-ion bond with the PBP resulting in inactivation of both the PBP and the drug.
    False, should say “Covalent”
  11. (True/False) Penicllins are bacteriocidal.
  12. The G+ cell wall is _____-______molecules thick.
  13. (True/False) The lipophilic nature of the penicillin is important for penetration of the G+ cell.
  14. The G- cell wall is ____-_____ molecules thick.
  15. The G+ cell wall contains porin channels that allow more polar molecules to penetrate.
    False, should say “G-“
  16. It is a balance between the ________and __________ that will determine the overall activity of a penicillin against either G- or G+.
    the lipophilic and polar nature
  17. The Lipophilic penicillins penetrate better through the thicker G+ or G- cell wall?
  18. Polar penicillins penetrate better through the G+ or G- cell wall, and why?
    G-, b/c the G- contains polar ion channels
  19. Bacteria gain antibiotic resistance via three main pathways, what are they?
    1.) Decrease affinity of the target molecule for the antibiotic 2.) Synthesize molecules which can hydrolyze the antibiotic 3.) G- change their membrane permeability to the antibiotic
  20. Between ___-___% of the population is allergic to Penicillins.
  21. Which penicillin are people most commonly allergic to?
  22. What are the mechanisms for allergenicity to penicillins?
    1.) -NH2 of Lysine in the PBP attacks the B-lactam producing allergenic penicilloyl proteins 2.) Polymerization occurs (usually w/ low pH) between Penicillins acyl N and the Carbonyl C of another penicillin producing an antigenic species
  23. What are the 5 classes of Penicillins?
    Natural, Penicillinase-resistant, Aminopenicillins, Anti-pseudomonal penicillins and Extended-spectrum penicillins
  24. What are the natural penicillins?
    Pen Gand V
  25. What are the Penicllinase-resistant penicllins?
    nafcillin, oxacillin , methicillin, cloxacillin and dicloxacillin
  26. Penicllinase-resistant penicllins are mainly active against what type of penicllinases?
    S. aureus
  27. What are the aminopenicllins?
    Amplicillin and amoxicillin
  28. What are the Anti-pseudomonal penicillins?
    Carbenicillin and ticarcillin
  29. What are the Extended-spectrum penicillins?
    Azlocillin, mezlocillin and piperacillin
  30. Natural Penicillins are mainly effective against G+ or G- bacteria?
    G+ (some G-)