Open AccessStructure of the iron complex in methemerythrin.
Author(s) -
Ronald E. Stenkamp,
L.C. Sieker,
L. H. Jensen
Publication year - 1976
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.73.2.349
Subject(s) - crystallography , side chain , chemistry , electron density , stereochemistry , protein subunit , sequence (biology) , electron , physics , biochemistry , polymer , organic chemistry , quantum mechanics , gene
The coordination of the ligands about the iron atoms in methemerythrin from Themiste dyscritum has been deduced from a 2.8 A resolution electron density map. The complex can be described in terms of two trigonal antiprisms about the pair of iron atoms in each subunit, the antiprisms having one face in common. Ligands at eight of the nine coordination positions are protein side chains, the ninth presumably being water. Comparison of the electron density map for T. dyscritum methemerythrin with the sequence of Phascolopsis gouldii hemerythrin suggests six aromatic side chain ligands (five histidine and one tyrosine) and two nonaromatic side chain ligands. The latter provide atoms at two of the three vertices of the face shared by the two antiprisms, and these along with the presumed water at the third vertex form bridges between the iron atoms of each pair.