Redox properties of cytochrome c nitrite reductase from Desulfovibrio desulfuricans ATCC 27774.
The dissimilatory nitrite reductase from Desulfovibrio desulfuricans ATCC 27774 catalyzes the reduction of nitrite to ammonia. Previous spectroscopic investigation revealed that it is a hexaheme cytochrome containing one high spin ferric heme and five low spin ferric hemes in the oxidized enzyme. The current study uses the high resolution of Mössbauer spectroscopy to obtain redox properties of the six heme groups. Correlating the Mössbauer findings with the EPR data reveals the pairwise spin-spin coupling among four of the heme groups. The other two hemes are found to be magnetically isolated. Reduction with dithionite and reaction with CO further indicate that only the high spin heme is capable of binding small exogenous ligands. These results confirm our previous finding that Desulfovibrio desulfuricans nitrite reductase contains six heme groups and that the high spin ferric heme is the substrate and inhibitor binding site.
Costa
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Departamento de Química and Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2825 Monte da Caparica, Portugal.
Moura
J J
JJ
Moura
I
I
Wang
Y
Y
Huynh
B H
BH
D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D045263:Cytochromes a1; D003575:Cytochromes c1; D003901:Desulfovibrio / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000737:chemistry / Q000378:metabolism*; D006864:Hydrogenase / Q000378:metabolism; D009565:Nitrate Reductases / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D015204:Spectroscopy, Mossbauer; D017186:Titrimetry
D006418:Heme; D002248:Carbon Monoxide; D045263:Cytochromes a1; D003575:Cytochromes c1; D006864:Hydrogenase; D009565:Nitrate Reductases; C054690:nitrate reductase (cytochrome)