<?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%">Moura, I.</style></author><author><style face="normal" font="default" size="100%">Tavares, P</style></author><author><style face="normal" font="default" size="100%">Moura, J. J.</style></author><author><style face="normal" font="default" size="100%">Ravi, N.</style></author><author><style face="normal" font="default" size="100%">Huynh, B. H.</style></author><author><style face="normal" font="default" size="100%">Liu, M. Y.</style></author><author><style face="normal" font="default" size="100%">Legall, J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Direct spectroscopic evidence for the presence of a 6Fe cluster in an iron-sulfur protein isolated from Desulfovibrio desulfuricans (ATCC 27774)</style></title><secondary-title><style face="normal" font="default" size="100%">J Biol Chem</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Amino Acid Sequence</style></keyword><keyword><style  face="normal" font="default" size="100%">Bacterial Proteins</style></keyword><keyword><style  face="normal" font="default" size="100%">Desulfovibrio/*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%">Electrophoresis, Polyacrylamide Gel</style></keyword><keyword><style  face="normal" font="default" size="100%">Iron-Sulfur Proteins/chemistry/*isolation &amp; purification</style></keyword><keyword><style  face="normal" font="default" size="100%">Iron/chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">Molecular Sequence Data</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Mar 5</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=1311311 </style></url></web-urls></urls><number><style face="normal" font="default" size="100%">7</style></number><volume><style face="normal" font="default" size="100%">267</style></volume><pages><style face="normal" font="default" size="100%">4489-96</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;A novel iron-sulfur protein was purified from the extract of Desulfovibrio desulfuricans (ATCC 27774) to homogeneity as judged by polyacrylamide gel electrophoresis. The purified protein is a monomer of 57 kDa molecular mass. It contains comparable amounts of iron and inorganic labile sulfur atoms and exhibits an optical spectrum typical of iron-sulfur proteins with maxima at 400, 305, and 280 nm. Mossbauer data of the as-isolated protein show two spectral components, a paramagnetic and a diamagnetic, of equal intensity. Detailed analysis of the paramagnetic component reveals six distinct antiferromagnetically coupled iron sites, providing direct spectroscopic evidence for the presence of a 6Fe cluster in this newly purified protein. One of the iron sites exhibits parameters (delta EQ = 2.67 +/- 0.03 mm/s and delta = 1.09 +/- 0.02 mm/s at 140 K) typical for high spin ferrous ion; the observed large isomer shift indicates an iron environment that is distinct from the tetrahedral sulfur coordination commonly observed for the iron atoms in iron-sulfur clusters and is consistent with a penta- or hexacoordination containing N and/or O ligands. The other five iron sites are most probably high spin ferric. Three of them show parameters characteristic for tetrahedral sulfur coordination. In correlation with the EPR spectrum of the as-purified protein which shows a resonance signal at g = 15.3 and a group of signals between g = 9.8 and 5.4, this 6Fe cluster is assigned to an unusual spin state of 9/2 with zero field splitting parameters D = -1.3 cm-1 and E/D = 0.062. Other EPR signals attributable to minor impurities are also observed at the g = 4.3 and 2.0 regions. The diamagnetic Mossbauer component represents a second iron cluster, which, upon reduction with dithionite, displays an intense S = 1/2 EPR signal with g values at 2.00, 1.83, and 1.31. In addition, an EPR signal of the S = 3/2 type is also observed for the dithionite-reduced protein.&lt;/p&gt;
</style></abstract><accession-num><style face="normal" font="default" size="100%">1311311</style></accession-num><notes><style face="normal" font="default" size="100%">&lt;p&gt;0021-9258 (Print)0021-9258 (Linking)Journal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.&lt;/p&gt;
</style></notes><auth-address><style face="normal" font="default" size="100%">Centro de Tecnologia Quimica e Biologica, Universidade Nova de Lisboa, Oeiras, Portugal.</style></auth-address></record></records></xml>