<?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%">Grazina, R.</style></author><author><style face="normal" font="default" size="100%">de Sousa, P. M.</style></author><author><style face="normal" font="default" size="100%">Brondino, C. D.</style></author><author><style face="normal" font="default" size="100%">Carepo, M. S.</style></author><author><style face="normal" font="default" size="100%">Moura, I.</style></author><author><style face="normal" font="default" size="100%">Moura, J. J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Structural redox control in a 7Fe ferredoxin isolated from Desulfovibrio alaskensis</style></title><secondary-title><style face="normal" font="default" size="100%">Bioelectrochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Bacterial Proteins/*chemistry/isolation &amp; purification</style></keyword><keyword><style  face="normal" font="default" size="100%">Desulfovibrio/*chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">Electrochemical Techniques</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Spin Resonance Spectroscopy</style></keyword><keyword><style  face="normal" font="default" size="100%">Electron Transport</style></keyword><keyword><style  face="normal" font="default" size="100%">Ferredoxins/*chemistry/isolation &amp; purification</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxidation-Reduction</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year><pub-dates><date><style  face="normal" font="default" size="100%">Aug</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=21600857 </style></url></web-urls></urls><number><style face="normal" font="default" size="100%">1</style></number><volume><style face="normal" font="default" size="100%">82</style></volume><pages><style face="normal" font="default" size="100%">22-8</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The redox behaviour of a ferredoxin (Fd) from Desulfovibrio alaskensis was characterized by electrochemistry. The protein was isolated and purified, and showed to be a tetramer containing one [3Fe-4S] and one [4Fe-4S] centre. This ferredoxin has high homology with FdI from Desulfovibrio vulgaris Miyazaki and Hildenborough and FdIII from Desulfovibrio africanus. From differential pulse voltammetry the following signals were identified: [3Fe-4S](+1/0) (E(0')=-158+/-5mV); [4Fe-4S](+2/+1) (E(0')=-474+/-5mV) and [3Fe-4S](0/-2) (E(0')=-660+/-5mV). The effect of pH on these signals showed that the reduced [3Fe-4S](0) cluster has a pK'(red)(')=5.1+/-0.1, the [4Fe-4S](+2/+1) centre is pH independent, and the [3Fe-4S](0/-2) reduction is accompanied by the binding of two protons. The ability of the [3Fe-4S](0) cluster to be converted into a new [4Fe-4S] cluster was proven. The redox potential of the original [4Fe-4S] centre showed to be dependent on the formation of the new [4Fe-4S] centre, which results in a positive shift (ca. 70mV) of the redox potential of the original centre. Being most [Fe-S] proteins involved in electron transport processes, the electrochemical characterization of their clusters is essential to understand their biological function. Complementary EPR studies were performed.&lt;/p&gt;
</style></abstract><accession-num><style face="normal" font="default" size="100%">21600857</style></accession-num><notes><style face="normal" font="default" size="100%">&lt;p&gt;1878-562X (Electronic)1567-5394 (Linking)Journal ArticleResearch Support, Non-U.S. Gov't&lt;/p&gt;
</style></notes><auth-address><style face="normal" font="default" size="100%">REQUIMTE/CQFB, Departamento de Quimica, Universidade Nova de Lisboa, Caparica, Portugal. raquel.grazina@dq.fct.unl.pt</style></auth-address></record></records></xml>