16 Questions
What is the role of an acid catalyst in the chemical modification of erythromycin?
Activating the hydroxyl group for a nucleophilic attack
What type of linkage is formed as a result of intramolecular nucleophilic attack in erythromycin?
Cyclic ketal linkage
How is the acid catalyst typically treated after its role in the chemical modification process with erythromycin?
Regenerated for further use
Which specific hydroxyl group in erythromycin is often selective for ketal formation?
C9 hydroxyl group
How does bacterial resistance to erythromycin and lincomycins occur?
By methylation of a specific adenine residue at the ribosomal subunit
Which characteristic of erythromycin is affected when the enzyme is produced by resistant strains?
Its binding to ribosomal RNA
Which chemical modification of erythromycin is associated with a pKa value around 7.5?
The conjugated phenolic enone system extending from C-10 to C-12
How do tetracyclines interfere with protein biosynthesis at the ribosomal level?
By inhibiting subsequent rRNA binding to the ribosomes
What is the main resistance mechanism of Gram-negative bacilli against macrolides like Erythromycin?
Increased permeability of the bacterial cell wall.
What is an alternative medical use of Erythromycin besides treating soft tissue infections?
Alternative for treating infections in patients allergic to penicillins.
Which chemical group is esterified at the keto group site in Erythromycin?
Desosamine
What is the major route of excretion for Erythromycin?
Bile
Which modification is made to increase lipid solubility and acid stability of Erythromycin for improved oral absorption?
Removal of 9-keto group
What feature distinguishes Azithromycin from other macrolides like Erythromycin?
15-membered lactone ring
Why do Enterobacteriaceae family bacteria show pH-dependent sensitivities to Erythromycin?
MIC's decrease with increasing pH.
What aspect was modified in Azithromycin to increase its stability to acid-catalyzed degradation?
Incorporation of tertiary amine nitrogen into the macrolide ring
Test your knowledge on the process of ketal formation within the MACROLIDES group of compounds, including the discovery of Erythromycin and its derivatives. Explore the common chemical characteristics shared by these compounds.
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