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Structural and functional relations among thioredoxins of different species
Author(s) -
Eklund Hans,
Gleason Florence K.,
Holmgren Arne
Publication year - 1991
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340110103
Subject(s) - thioredoxin , active site , biochemistry , isomerase , protein disulfide isomerase , amino acid , protein structure , protein secondary structure , peptide sequence , conserved sequence , escherichia coli , sequence alignment , protein superfamily , stereochemistry , chemistry , biology , enzyme , gene
Three‐dimensional models have been constructed of homologous thioredoxins and protein disulfide isomerases based on the high resolution x‐ray crystallographic structure of the oxidized form of Escherichia coli thioredoxin. The thioredoxins, from archebacteria to humans, have 27–69% sequence identity to E. coli thioredoxin. The models indicate that all the proteins have similar three‐dimensional structures despite the large variation in amino acid sequences. As expected, residues in the active site region of thioredoxins are highly conserved. These include Asp‐26, Ala‐29, Trp‐31, Cys‐32, Gly‐33, Pro‐34, Cys‐35, Asp‐61, Pro‐76, and Gly‐92. Similar residues occur in most protein disulfide isomerase sequences. Most of these residues form the surface around the active site that appears to facilitate interactions with other enzymes. Other structurally important residues are also conserved. A proline at position 40 causes a kink in the alpha‐2 helix and thus provides the proper position of the active site residues at the amino end of this helix. Pro‐76 is important in maintaining the native structure of the molecule. In addition, residues forming the internal contact surfaces between the secondary structural elements are generally unchanged such as Phe‐12, Val‐25, and Phe‐27.