<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Pereira, AS</style></author><author><style face="normal" font="default" size="100%">Timoteo, C. G.</style></author><author><style face="normal" font="default" size="100%">Guilherme, M.</style></author><author><style face="normal" font="default" size="100%">Folgosa, F</style></author><author><style face="normal" font="default" size="100%">Naik, S. G.</style></author><author><style face="normal" font="default" size="100%">Duarte, A. G.</style></author><author><style face="normal" font="default" size="100%">HUYNH, BH</style></author><author><style face="normal" font="default" size="100%">Tavares, P.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Spectroscopic evidence for and characterization of a trinuclear ferroxidase center in bacterial ferritin from Desulfovibrio vulgaris Hildenborough</style></title><secondary-title><style face="normal" font="default" size="100%">J Am Chem Soc</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Journal of the American Chemical Society</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Bacterial Proteins/chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">Ceruloplasmin/chemistry/*metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Desulfovibrio vulgaris/metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Spin Resonance Spectroscopy</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferritins/chemistry/*metabolism</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferrous Compounds/chemistry/*metabolism</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2012</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Jul 4</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&amp;db=PubMed&amp;dopt=Citation&amp;list_uids=22681596 </style></url></web-urls></urls><number><style face="normal" font="default" size="100%">26</style></number><volume><style face="normal" font="default" size="100%">134</style></volume><pages><style face="normal" font="default" size="100%">10822-32</style></pages><isbn><style face="normal" font="default" size="100%">1520-5126 (Electronic)0002-7863 (Linking)</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Ferritins are ubiquitous and can be found in practically all organisms that utilize Fe. They are composed of 24 subunits forming a hollow sphere with an inner cavity of ~80 A in diameter. The main function of ferritin is to oxidize the cytotoxic Fe(2+) ions and store the oxidized Fe in the inner cavity. It has been established that the initial step of rapid oxidation of Fe(2+) (ferroxidation) by H-type ferritins, found in vertebrates, occurs at a diiron binding center, termed the ferroxidase center. In bacterial ferritins, however, X-ray crystallographic evidence and amino acid sequence analysis revealed a trinuclear Fe binding center comprising a binuclear Fe binding center (sites A and B), homologous to the ferroxidase center of H-type ferritin, and an adjacent mononuclear Fe binding site (site C). In an effort to obtain further evidence supporting the presence of a trinuclear Fe binding center in bacterial ferritins and to gain information on the states of the iron bound to the trinuclear center, bacterial ferritin from Desulfovibrio vulgaris (DvFtn) and its E130A variant was loaded with substoichiometric amounts of Fe(2+), and the products were characterized by Mossbauer and EPR spectroscopy. Four distinct Fe species were identified: a paramagnetic diferrous species, a diamagnetic diferrous species, a mixed valence Fe(2+)Fe(3+) species, and a mononuclear Fe(2+) species. The latter three species were detected in the wild-type DvFtn, while the paramagnetic diferrous species was detected in the E130A variant. These observations can be rationally explained by the presence of a trinuclear Fe binding center, and the four Fe species can be properly assigned to the three Fe binding sites. Further, our spectroscopic data suggest that (1) the fully occupied trinuclear center supports an all ferrous state, (2) sites B and C are bridged by a mu-OH group forming a diiron subcenter within the trinuclear center, and (3) this subcenter can afford both a mixed valence Fe(2+)Fe(3+) state and a diferrous state. Mechanistic insights provided by these new findings are discussed and a minimal mechanistic scheme involving O-O bond cleavage is proposed.&lt;/p&gt;
</style></abstract><accession-num><style face="normal" font="default" size="100%">22681596</style></accession-num><notes><style face="normal" font="default" size="100%">&lt;p&gt;GM47295/GM/NIGMS NIH HHS/United StatesJournal ArticleResearch Support, N.I.H., ExtramuralResearch Support, Non-U.S. Gov'tUnited States&lt;/p&gt;
</style></notes><auth-address><style face="normal" font="default" size="100%">Requimte/CQFB, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica, Portugal. masp@fct.unl.pt</style></auth-address></record></records></xml>