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Publication Abstract from PubMed

Transferrin, the Fe(III) transport protein in mammalian blood, has been suggested to also serve as a Cr(III) transporter and as part of a Cr(III) detoxification system; however, the structure of the metal-binding sites has never been fully elucidated with bound Cr(III). Chromium(III)-transferrin was crystallized in the presence of the synergistic anion malonate. In the crystals, the protein exists with a closed C-terminal lobe containing a Cr(III) ion and an open, unoccupied N-terminal lobe. The overall structure and the metal ion environments are extremely similar to those of Fe(III)- and Ti(IV)-containing transferrin crystallized under comparable conditions. The octahedral coordination about the Cr(III) is comprised of four ligands provided by the protein (two tyrosine residues, a histidine residue, and an aspartate residue) and a chelating malonate anion. This represents the first crystal structure of a Cr(III)-containing protein that binds Cr(III) as part of its physiological function.

X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein.,Petersen CM, Edwards KC, Gilbert NC, Vincent JB, Thompson MK J Inorg Biochem. 2020 Sep;210:111101. doi: 10.1016/j.jinorgbio.2020.111101. Epub , 2020 May 23. PMID:32650146^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.