氯霉素，大包装

Chemical structure: phenicole

Chloramphenicol is a synthetic antibiotic, isolated from strains of Streptomyces venezuelae. It is often used for bacterial selection in molecular biology applications at 10-20 μg/mL and as a selection agent for transformed cells containing chloramphenicol reistance genes.

作用机制：氯霉素通过与50S核糖体亚基结合并阻止氨酰基tRNA附着于核糖体来阻断肽基转移酶步骤，从而抑制细菌蛋白质的合成。 它还抑制线粒体和叶绿体蛋白的合成以及（p）ppGpp的核糖体形成，从而抑制rRNA的转录。

耐药性机制：使用氯霉素乙酰转移酶会使产物乙酰化并使其失活。

抗菌谱：这是一种针对革兰氏阳性和革兰氏阴性细菌的广谱抗生素，主要用于眼科和兽医目的。

Stock solutions can be prepared directly in the vial at any recommended concentration. A solution at 50 mg/mL in ethanol yields a clear, very faint, yellow solution. Degradation of chloramphenicol in aqueous solution is catalyzed by general acids and bases. This rate of degradation is independent of the ionic strength and pH.

Stock solutions should be stored at 2-8°C and are stable at 37°C for 5 days. Aqueous solutions are neutral and stable over a wide pH range, with 50% hydrolysis occurring after 290 days. Use of a borax buffered solution reduces this number to 14%. Solutions should be protected from light as photochemical decomposition results in a yellowing of the solution. Heating aqueous solutions at 115°C for 30 minutes results in a 10% loss of chloramphenicol.