TY - JOUR
T1 - Structural redox control in a 7Fe ferredoxin isolated from Desulfovibrio alaskensis
AU - Moura, José João Galhardas de
AU - Videira, Patrícia de Mira Paes de Sousa
AU - Moura, Isabel Maria Andrade Martins Galhardas de
AU - Carepo, Marta Sofia Peixe
PY - 2011/1/1
Y1 - 2011/1/1
N2 - 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 Fdl 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 +/- 5 mV); [4Fe-45](+2/+1) (E(0')=-474 +/- 5 mV) and [3Fe-4S](0/-2) ( E(0')=-660 +/- 5 mV). 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. 70 mV) 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.
AB - 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 Fdl 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 +/- 5 mV); [4Fe-45](+2/+1) (E(0')=-474 +/- 5 mV) and [3Fe-4S](0/-2) ( E(0')=-660 +/- 5 mV). 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. 70 mV) 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.
KW - Electrochemistry
KW - 7Fe ferredoxins
KW - Iron-sulfur clusters
KW - Desulfovibrio bacteria
U2 - 10.1016/j.bioelechem.2011.04.005
DO - 10.1016/j.bioelechem.2011.04.005
M3 - Article
C2 - 21600857
SN - 1567-5394
VL - 82
SP - 22
EP - 28
JO - Bioelectrochemistry
JF - Bioelectrochemistry
IS - 1
ER -