title: The crystal structure and amino acid sequence of dehaloperoxidase from Amphitrite ornata indicate common ancestry with globins.
abstract: The full-length, protein coding sequence for dehaloperoxidase was obtained using a reverse genetic approach and a cDNA library from marine worm Amphitrite ornata. The crystal structure of the dehaloperoxidase (DHP) was determined by the multiple isomorphous replacement method and was refined at 1.8-A resolution. The enzyme fold is that of the globin family and, together with the amino acid sequence information, indicates that the enzyme evolved from an ancient oxygen carrier. The peroxidase activity of DHP arose mainly through changes in the positions of the proximal and distal histidines relative to those seen in globins. The structure of a complex of DHP with 4-iodophenol is also reported, and it shows that in contrast to larger heme peroxidases DHP binds organic substrates in the distal cavity. The binding is facilitated by the histidine swinging in and out of the cavity. The modeled position of the oxygen atom bound to the heme suggests that the enzymatic reaction proceeds via direct attack of the oxygen atom on the carbon atom bound to the halogen atom.
authors.affiliation: Departments of Chemistry and Biochemistry and Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: LaCount
authors.forename: E
authors.initials: E
authors.lastname: Zhang
authors.forename: Y P
authors.initials: YP
authors.lastname: Chen
authors.forename: K
authors.initials: K
authors.lastname: Han
authors.forename: M M
authors.initials: MM
authors.lastname: Whitton
authors.forename: D E
authors.initials: DE
authors.lastname: Lincoln
authors.forename: S A
authors.initials: SA
authors.lastname: Woodin
authors.forename: L
authors.initials: L
authors.lastname: Lebioda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D006454:Hemoglobins; D008969:Molecular Sequence Data; D010544:Peroxidases / Q000737:chemistry* / Q000235:genetics; D011077:Polychaeta / Q000201:enzymology*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D006454:Hemoglobins; C098661:DHP I dehaloperoxidase; D010544:Peroxidases