Any of a class of coordination or complex compounds consisting of a central atom of a metal (usually a transition element) attached to a large molecule (ligand). Any ligand that can bind to the metal at two or more points to form a ring structure, more stable than a nonchelated compound of the same general chemical formula, is a chelating agent. The process of binding to the metal is called chelation. Chelating agents such as EDTA salts are used in medicine to remove toxic metals (e.g., lead, cadmium) from the body. Others are used in analysis as indicators and in industry to extract metals. The iron-binding porphyrin group in hemoglobin, the magnesium-binding porphyrin in chlorophyll, and the cobalt-binding porphyrin in vitamin B12 are natural chelators.

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In enzymology, an iron-chelate-transporting ATPase is an enzyme that catalyzes the chemical reaction

ATP + H2O + iron chelateout rightleftharpoons ADP + phosphate + iron chelatein

The 3 substrates of this enzyme are ATP, H2O, and iron chelate, whereas its 3 products are ADP, phosphate, and iron chelate.

This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (iron-chelate-importing). This enzyme participates in abc transporters - general.

Structural studies

As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .


  • Shea CM, McIntosh MA "Nucleotide sequence and genetic organization of the ferric enterobactin transport system: homology to other periplasmic binding protein-dependent systems in Escherichia coli". Mol. Microbiol. 5 1415–28.
  • Koster W, Bohm B "Point mutations in two conserved glycine residues within the integral membrane protein FhuB affect iron(III) hydroxamate transport". Mol. Gen. Genet. 232 399–407.
  • Kuan G, Dassa E, Saurin W, Hofnung M, Saier MH Jr "Phylogenetic analyses of the ATP-binding constituents of bacterial extracytoplasmic receptor-dependent ABC-type nutrient uptake permeases". Res. Microbiol. 146 271–8.
  • Saier MH Jr "Molecular phylogeny as a basis for the classification of transport proteins from bacteria, archaea and eukarya". Adv. Microb. Physiol. 40 81–136.
  • Mademidis A, Koster W "Transport activity of FhuA, FhuC, FhuD, and FhuB derivatives in a system free of polar effects, and stoichiometry of components involved in ferrichrome uptake". Mol. Gen. Genet. 258 156–65.

External links

Gene Ontology (GO) codes

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