Mechanism of Action of a 16‐Membered Macrolide

Abstract
Rosaramicin is a new macrolide antibiotic with activity similar to that of erythromycin. In this paper, we describe the synthesis of [3H]dihydrorosaramicin and show by sucrose gradient centrifugation, gel exclusion chromatography and equilibrium dialysis that rosaramicin and its dihydroderivative bind specifically to the 70‐S ribosome and 50‐S ribosomal subunit of Escherichia coli. Binding to the 30‐S subunit is not detectable. The parameters of the binding interaction were evaluated by equilibrium dialysis. The affinities of E. coli ribosomes for rosaramicin and dihydrorosaramicin are in good agreement with the mininal inhibitory concentration of these drugs for microorganisms.