Tetraglycylferrichrome ‐ the first heptapeptide ferrichrome

From a strain of Neovossia indien (Mitra) Mundk., a smut fungus of the order Tilletiales, a novel ferrichrome‐type siderophore was isolated. We have demonstrated that this is a heptapeptide rather than the usual hexapeptide, which contained, in addition to L‐ornithine, a (Gly)4 sequence instead of the (Gly)3 sequence usually found. Transport studies with 55Fe‐labelled (Gly)4‐ferrichrome and (Gly)3‐ferrichrome in Neurospora crassa revealed identical uptake rates, indicating that increased ring size and conformational flexibility of the peptide backbone are of minor importance during function and recognition by the ferrichrome transport system.