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Flavodoxin hydroquinone reduces Azotobacter vinelandii Fe protein to the all-ferrous redox state with a S = 0 spin state.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lowery, Thomas J. Zhang, Bo Bunker, Jared Nyborg, Andrew C. Thiriot, David S. |
| Copyright Year | 2006 |
| Abstract | Azotobacter vinelandii flavodoxin hydroquinone (FldHQ) is a physiological reductant to nitrogenase supporting catalysis that is twice as energy efficient (ATP/2e- = 2) as dithionite (ATP/2e- = 4). This catalytic efficiency results from reduction of Fe protein from A. vinelandii (Av2) to the all-ferrous oxidation state ([Fe4S4]0), in contrast to dithionite, which only reduces Av2 to the [Fe4S4]1+ state. Like FldHQ, Ti(III) citrate yields ATP/2e- = 2, and Ti(III)-reduced [Fe4S4]0 Av2 has a S = 4 spin state and characteristic Mossbauer spectrum, a parallel mode g = 16.4 EPR signal, and a shoulder at 520 nm in its UV-vis spectrum, each of which distinguish the S = 4 [Fe4S4]0 Av2 from other states. In this study, we demonstrate that FldHQ makes [Fe4S4]0 Av2, which is sufficiently characterized to demonstrate unique physical properties that distinguish it from the previously characterized Ti(III)-reduced [Fe4S4]0 Av2. In particular, Evans NMR magnetic susceptibility and EPR measurements indicate that FldHQ-reduced [Fe4S4]0 Av2 has an S = 0 spin state (like [Fe4S4]2+ Av2). There is no g = 16.4 EPR signal and no shoulder at 520 nm in its absorbance spectrum, which resembles that of [Fe4S4]1+ Av2. That the physiological reductant to Av2 is capable of forming [Fe4S4]0 Av2 has important implications for in vivo nitrogenase activity. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.pnas.org/content/103/46/17131.full.pdf |
| PubMed reference number | 17085583v1 |
| Volume Number | 103 |
| Issue Number | 46 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Bacillus sp. AV2-9 Dithionite Ferrous FesII protein, Azotobacter vinelandii Flavodoxin Iron Nitrogenase Oxidation-Reduction Physical Phenomenon or Property hydroquinone 20 MG/ML Topical Cream oxidation sodium citrate |
| Content Type | Text |
| Resource Type | Article |
