Crystal and Molecular Structure of Ferrichrome A.

The crystal structure of ferrichrome A (C(41)H(58)N(9)O(20)Fe.4H(2)O) has been determined by x-ray diffraction. The amino acid sequence in the hexapeptide ring is confirmed to be -Orn-Orn-Orn-Ser-Ser-Gly-, and the conformation of this ring is trans at each peptide linkage. The absolute configuration of the three hydroxamate rings at the iron atom is that of a left-handed propeller. Disorder is found concerning the positions of some of the side chains and one of the four water molecules.