Dalfopristin

Dalfopristin is a semisynthetic polyunsaturated macrolactone type II streptogramin antibiotic protein synthesis inhibitor. It is generally used in combination with Quinupristin. Dalfopristin inhibits the early phase of protein synthesis in the bacterial ribosome and quinupristin inhibits the late phase of protein synthesis, thus the two together act synergistically. Dalfopristin binds to the 23S portion of the 50S ribosomal subunit, and changes the conformation, enhancing the binding of quinupristin. In addition, it inhibits peptidyl transfer. Quinupristin binds to a nearby site on the 50S ribosomal subunit and prevents elongation of the polypeptide, as well as causing incomplete chains to be released. Each alone is only bacteriostatic; the combination is bactericidal.