Sandbox Reserved 460: Difference between revisions
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=Nitrite Reductase= | =Nitrite Reductase= | ||
=='''General Information'''== | |||
Nitrogen is an essential element for plant growth and development. Many plants form symbiotic relationships with bacteria and fungi to fix elemental nitrogen from the atmosphere to a deliverable form for the plants to use. Other plants have enzymes that can reduce nitrates in the soil to ammonium. | |||
=='''Overview'''== | =='''Overview'''== | ||
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Nitrite reductase is an enzyme that belongs to the Oxidoreductase family for catalyzing the six-electron reduction of nitrite into ammonia, using the reduced ferredoxin as the electron donor. It is a monomeric protein with molecular mass near 63 kDa characterized by a unique <scene name='Sandbox_Reserved_460/Active_site/3'>active site</scene> which contains a single [4Fe–4S] cluster and a single siroheme (which serves as the binding site for nitrite) via a bridging sulfur atom from a cysteine residue. The protein has a globular fold consisting of 3 alpha/beta domains with the siroheme-iron sulfur cofactor at the interface of the three domains. The siroheme is surrounded by several ionizable amino acid residues that facilitate the binding and subsequent reduction of nitrite. | |||
Nitrite reductase is found in several organisms and different forms that reduce nitrite to various products. The enzyme to the right contains a siroheme and iron-sulfur cluster to reduce nitrite to ammonia in certain plants. It is found in the stromal space of chloroplasts. Several other types of iron-based enzymes in bacteria reduce nitrite to nitrous oxide. There are also several types of Copper Nitrite Reductases found in many different plants and bacteria. | |||
=='''Mechanism'''== | =='''Mechanism'''== | ||
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[[Image:Pathway.jpeg]] | ::[[Image:Pathway.jpeg]] | ||
=='''Structure'''== | =='''Structure'''== | ||
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<scene name='Sandbox_Reserved_460/Siroheme/1'>Siroheme</scene> is an iron-containing, modified tetrapyrrole similar in structure to both heme and chlorophyll. It is a heme-like prosthetic group used by nitrite reductase to carry out the six-electron reduction of nitrogen. Nitrite is reduced to ammonia while still bound to siroheme. | <scene name='Sandbox_Reserved_460/Siroheme/1'>Siroheme</scene> is an iron-containing, modified tetrapyrrole similar in structure to both heme and chlorophyll. It is a heme-like prosthetic group used by nitrite reductase to carry out the six-electron reduction of nitrogen. Nitrite is reduced to ammonia while still bound to siroheme. | ||
The siroheme-iron sulfur cofactor is at the interface of the three domains of the enzyme. The siroheme is surrounded by several ionizable amino acid residues that facilitate the binding and subsequent reduction of nitrite. | The siroheme-iron sulfur cofactor is at the interface of the three domains of the enzyme. The siroheme is surrounded by several ionizable amino acid residues that facilitate the binding and subsequent reduction of nitrite. | ||
===Ligand Binding to Active Sites=== | ===Ligand Binding to Active Sites=== | ||
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* <scene name='Sandbox_Reserved_460/Ac5/2'>AC5</scene> binds Chloride ion | * <scene name='Sandbox_Reserved_460/Ac5/2'>AC5</scene> binds Chloride ion | ||
* <scene name='Sandbox_Reserved_460/Ac6/2'>AC6</scene> binds Nitrite | * <scene name='Sandbox_Reserved_460/Ac6/2'>AC6</scene> binds Nitrite | ||
=='''References'''== | |||
