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#antibiotic mechanism

2 public questions tagged with this topic.

Microbial Physiology

Which enzyme is inhibited by penicillin?

Bacterial peptidoglycan final crosslinking step catalyzed by transpeptidases penicillin binding proteins class B enzymes PBP2 for elongation, PBP3 FtsI for division. They cleave C terminal D alanine D alanine dipeptide from pentapeptide side chain MurNAc L Ala D Glu mDAP D Ala D Ala, forming acyl enzyme intermediate through active site serine nucleophile, then transfer to amino group acceptor meso diamino pimelic acid or L lysine of neighboring strand creating peptide crossbridge essential for wall rigidity. Beta lactam antibiotics penicillin contain four membered ring mimicking D Ala D Ala co

Ref: Tipper & Strominger, PNAS 1965, Penicillin inhibits transpeptidase PBP crosslinking peptidoglycan.

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Microbial Physiology

The mechanism of action of macrolides (e.g., erythromycin) is:

Macrolides such as erythromycin, azithromycin and clarithromycin belong to group characterized by large 14-, 15- or 16-membered lactone rings decorated with deoxy sugar moieties L-cladinose and desosamine that confer binding specificity. They lodge within the nascent peptide exit tunnel of the large ribosomal subunit. Bacterial ribosomes comprise small 30S and large 50S subunits; 50S contains 23S rRNA that forms the peptidyl transferase center and tunnel spanning subunit. Macrolides bind at nucleotides 2058 and 2059 of domain V of 23S rRNA near the peptidyl transferase center, partially occlud

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 7: Macrolides Binding to 50S Ribosomal Subunit.

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