Chloramphenicol

Biochemical / physiological behavior.
Mode of action: chloramphenicol blocks the peptidyl transferase step by binding to 50s ribosomal subunits and blocking the connection of aminoacyl tRNA with ribosomes, thus inhibiting bacterial protein synthesis. It also inhibits mitochondrial and chloroplast protein synthesis and ribosome formation (p) ppGpp, and inhibits rRNA transcription. Resistance model: chloramphenicol acetyltransferase was used to acetylate it and inactivate it. Antibacterial spectrum: this is a broad-spectrum antibiotic against Gram-positive and Gram-negative bacteria, mainly used in ophthalmology and veterinarians.

Points for attention in preparation.
The solution of 50mg / mL in ethanol produces a clear, very light yellow solution. General acids and bases catalyze the degradation of chloramphenicol in aqueous solution. The degradation rate has nothing to do with ionic strength and pH.

Warning.
The stored solution should be stored at 2-8 ℃ and stable for 5 days at 37 ℃. The aqueous solution is neutral and stable in a large range of pH, and 50% hydrolysis occurs after 290 days. This amount can be reduced to 14% by using borax buffer solution. Due to the yellowing of the solution caused by photochemical decomposition, the solution should be protected from light. Heating the aqueous solution at 115 ℃ for 30 minutes will result in a 10% loss of chloramphenicol.

Application.
Chloramphenicol is a synthetic antibiotic isolated from Streptomyces venezuelae strain of Venezuela. It is usually used in the selection of bacteria in molecular biology applications at a concentration of 10-20 ug / mL and as a selector for transformed cells containing chloramphenicol resistance genes.