Interaction of RNA Polymerase with Rifamycin

The rifamycins, together with the streptovaricins and tolypomycin form a novel class of antibiotics which have in common some structural features as well as the unique property of inhibiting specifically RNA polymerase of bacterial but not of mammalian origin. The chemical similarity between rifamycin [1], streptovaricins [2], and tolypomycin [3] lies in the fact that they are all ansa-compounds, i.e. compounds containing an aromatic ring system which is spanned by an aliphatic bridge. For this reason the name “ansamycins” has recently been proposed for these antibiotics [4].