The enzymatic acetylation of chloramphenicol by extracts of R factor-resistant Escherichia coli.

Chloramphenicol-resistant strains of Escherichia coli which carry the episomal resistance transfer factor R inactivate the antibiotic by enzymatic acetylation. In the presence of chloramphenicol and acetyl coenzyme A, cell extracts catalyze the formation of both a monoacetyl and a diacetyl derivative of chloramphenicol. Definitive identification of the reaction products as 3-acetoxy chloramphenicol and 1,3diacetoxy chloramphenicol was possible with the use of thin layer chromatography and ultraviolet spectroscopy. A simple spectrophotometric assay of acetylation has been devised based on the disappearance of acetyl coenzyme A. Preliminary kinetic data for the acetylation of chloramphenico1 and related compounds are presented.