Nitrogenase: Difference between revisions
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<StructureSection load="1N2C" size="350" color="white" caption="Nitrogenase complex: α (grey and green) and β (pink and yellow) chains, nitrogenase iron protein ( purple,cyan, red and gold), showing Fe-Mo-S cluster complex with ADP, adipic acid, AlF4, Ca+2 and Mg+2 ions [[1n2c]]"> | <StructureSection load="1N2C" size="350" color="white" caption="Nitrogenase complex: α (grey and green) and β (pink and yellow) chains, nitrogenase iron protein ( purple,cyan, red and gold), showing Fe-Mo-S cluster complex with ADP, adipic acid, AlF4, Ca+2 and Mg+2 ions [[1n2c]]"> | ||
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==Function== | |||
'''Nitrogenase''' (Nase) is an enzyme that fixes atmospheric nitrogen (N<sub>2</sub>) into ammonia. Though abundantly present in the atmosphere, most organisms cannot utilize N<sub>2</sub> directly, and must instead take it in through other forms, like ammonia or nitrate. The triple bond in N<sub>2</sub> is highly resistant to changes in oxidation state, and nitrogenases, found only in nitrogen-fixing bacteria, are the only proteins capable of reducing N<sub>2</sub> to ammonia. | '''Nitrogenase''' (Nase) is an enzyme that fixes atmospheric nitrogen (N<sub>2</sub>) into ammonia. Though abundantly present in the atmosphere, most organisms cannot utilize N<sub>2</sub> directly, and must instead take it in through other forms, like ammonia or nitrate. The triple bond in N<sub>2</sub> is highly resistant to changes in oxidation state, and nitrogenases, found only in nitrogen-fixing bacteria, are the only proteins capable of reducing N<sub>2</sub> to ammonia. | ||
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For these reasons, binding of Fe protein to FeMo protein results in hydrolysis of ATP. Additionally, the 4Fe:4S cluster is lowered close enough to the metal-sulfur clusters of the FeMo protein that electron transfer can occur. All three clusters found in the Fe protein-FeMo protein complex can be seen <scene name='Sandbox_10/1n2c_clusters/2'>here</scene>. Once the electrons have passed from the 4Fe:4S cluster of the Fe protein to the 8Fe:7S cluster of the FeMo protein, they then transfer to the 7Fe:Mo:9S:homocitrate:X cluster where X is an unidentified light atom. It is at this cluster where reduction of N<sub>2</sub> and H<sup>+</sup> occur. The exact mechanism of reduction, however, is still unknown. | For these reasons, binding of Fe protein to FeMo protein results in hydrolysis of ATP. Additionally, the 4Fe:4S cluster is lowered close enough to the metal-sulfur clusters of the FeMo protein that electron transfer can occur. All three clusters found in the Fe protein-FeMo protein complex can be seen <scene name='Sandbox_10/1n2c_clusters/2'>here</scene>. Once the electrons have passed from the 4Fe:4S cluster of the Fe protein to the 8Fe:7S cluster of the FeMo protein, they then transfer to the 7Fe:Mo:9S:homocitrate:X cluster where X is an unidentified light atom. It is at this cluster where reduction of N<sub>2</sub> and H<sup>+</sup> occur. The exact mechanism of reduction, however, is still unknown. | ||
==3D structure of Nitrogenase== | ==3D structure of Nitrogenase== | ||
[[Nitrogenase 3D structures]] | [[Nitrogenase 3D structures]] | ||