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Hydrating the Bispropionate Notch in Malaria Pigment: A New Structural Motif in the Iron(III)(deuteroporphyrin) Dimer
Author(s) -
Kuter David,
Suárez Liliana,
Dodd Erin L.,
Noll Bruce C.,
Stephens Peter W.,
Bohle D. Scott
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805116
Subject(s) - motif (music) , dimer , pigment , malaria , chemistry , stereochemistry , biology , art , immunology , organic chemistry , aesthetics
Treating deuterohemin, chloro(deuteroporphyrinato)iron(III), with a non‐coordinating base in DMSO/methanol allows for the isolation of [(deuteroporphyrinato)iron(III)] 2 , deuterohematin anhydride (DHA), an analogue of malaria pigment, the natural product of heme detoxification by malaria. The structure of DHA obtained from this solvent system has been solved by X‐ray powder diffraction analysis and displays many similarities, yet important structural differences, to malaria pigment. Most notably, a water molecule of solvation occupies a notch created by the propionate side chains and stabilizes a markedly bent propionate ligand coordinated with a long Fe−O bond, and a carboxylate cluster associated with water molecules is generated. Together, these features account for its increased solubility and more open structure, with an increased porphyrin–porphyrin separation. The IR spectroscopic signature associated with this structure also accounts for the strong IR band at 1587 cm −1 seen for many amorphous preparations of synthetic malaria pigment, and it is proposed that stabilizing these structures may be a new objective for antimalarial drugs. The important role of the vinyl substituents in this biochemistry is further demonstrated by the structure of deuterohemin obtained by single‐crystal X‐ray diffraction analysis.