SECTION A

Tetracyclines bind to the 30S subunit of microbial ribosomes. They prevent protein synthesis by blocking the attachment of the charged amino acyl-tRNA to the A site on the ribosome. They prevent the introduction of new amino acids to the nascent peptide chain. Uses Tetracycline has a bacteriostatic activity against aerobic and anaerobic bacterial species. It…

Tetracycline is a broad-spectrum antibiotic produced by the Streptomyces genus of actinobacteria used against various bacterial infections. The tetracyclines were discovered as natural products by Benjamin Minge Duggar in 1945. Refer Figure 13.4 for the structure of tetracycline. Figure 13.4 Structure of Tetracycline

Chloramphenicol is a bacteriostatic drug and it inhibits bacterial growth. It controls the bacterial growth by inhibiting protein synthesis. Chloramphenicol controls the protein chain elongation by inhibiting the peptidyl transferase activity of the bacterial ribosome. It specifically binds to the 23S rRNA of the 50S ribosomal subunit, thereby preventing the peptide–bond formation. Uses Chloramphenicol is…

The molecular formula of chloramphenicol is C11H12Cl2N2O5 (refer Figure 13.3). It is soluble in lipid. It remains unbound to protein. Figure 13.3 Structure of Chloramphenicol

Chloramphenicol (Chloromycetin) is a bacteriostatic antimicrobial. It is considered as a broad-spectrum antibiotic. Chloramphenicol is active against a wide variety of Gram-positive and Gram-negative bacteria including anaerobic organisms. Chloramphenicol was derived from the bacterium Streptomyces venezuelae, and it was isolated by David Gottlieb.

Streptomycin is used for treating tuberculosis in combination with other anti-TB drugs. It is also used as a pesticide to combat the growth of bacteria, fungi and algae. It controls bacterial and fungal diseases of certain fruits, vegetables, seeds and ornamental crops.

Streptomycin is an inhibitor of protein synthesis. It binds to the small 16S rRNA of the 30S subunit of the bacterial ribosome, and binds to formyl-methionyl-tRNA. This leads to codon misreading and hence ultimately the death of microbial cells. The human ribosomes are different from that of bacterial ribosomes; this makes the antibiotic selective only for…