Stereochemical aspects of iron transport in Mycelia sterilia EP-76.

Chromic complexes of N,N',N''-triacetylfusarinine C have been prepared and examined for biological activity in Mycelia sterilia EP-76. The iron transport system of this organism recognizes only the lambda coordination isomer of Cr(III)-triacetylfusarinine C even though the delta configuration predominates in solution. Chromium is excreted into the medium following triacetylfusarinine C-mediated uptake of the metal. Hydrogenation of the double bonds conjugated to the hydroxamic acid functions of triacetylfusarinine C yields four chromatographically distinct ferric complexes. Two of the complexes have the lambda configuration, while the other two have the opposite (delta) configuration. The complexes differ in effectiveness as siderophores in M. sterilia EP-76, the lambda isomers being most active.