Sandbox reserved 457: Difference between revisions
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== Function == | == Function == | ||
The ferrous form of Lb has a very high affinity for oxygen. Nitrogenase is the enzyme responsible for nitrogen fixation, however it is inactivated by oxygen. Bacteroids need oxygen for energy in order to reduce nitrogen to ammonia. This process is known as '''facilitated diffusion'''. The amount of oxygenated Lb present in the nodules can be estimated using spectroscopy. Deoxygenated ferrous Lb has an absorption maxima at 427 and 555 nm. In comparison, oxygenated ferrous Lb has an absorption maxima at 411, 541 and 575 nm. Ferric Lb exhibits a characteristic peak at 625 nm.<ref>http://digital.csic.es/bitstream/10261/4277/1/analesv.21n.3-1995-pp203.pdf</ref> | The ferrous form of Lb has a very high affinity for oxygen. Nitrogenase is the enzyme responsible for nitrogen fixation, however it is inactivated by oxygen. Bacteroids need oxygen for energy in order to reduce nitrogen to ammonia. This process is known as '''facilitated diffusion'''. The amount of oxygenated Lb present in the nodules can be estimated using spectroscopy. Deoxygenated ferrous Lb has an absorption maxima at 427 and 555 nm. In comparison, oxygenated ferrous Lb has an absorption maxima at 411, 541 and 575 nm. Ferric Lb exhibits a characteristic peak at 625 nm.<ref>http://digital.csic.es/bitstream/10261/4277/1/analesv.21n.3-1995-pp203.pdf</ref> | ||
== Structure == | == Structure == | ||
The secondary structure contains 2 identical amino acid chains with 143 residues per chain. It also contains 14 alpha helices per chain and no beta sheets. Deoxy-leghemoglobin has a proximal histidine. The imidazole rotates between two different positions, forming an eclipsed position. The proximal histidine increases the steric hindrance, while it has a staggered position in oxy-leghemoglobin. These opposite positions between oxy- and deoxy- leghemoglobin allow for a reduced activation energy for the reaction between leghemoglobin and oxygen. <ref>http://www.rcsb.org/pdb/explore/explore.do?structureId=2GDM<ref> | The secondary structure contains 2 identical amino acid chains with 143 residues per chain. It also contains 14 alpha helices per chain and no beta sheets. Deoxy-leghemoglobin has a proximal histidine. The imidazole rotates between two different positions, forming an eclipsed position. The proximal histidine increases the steric hindrance, while it has a staggered position in oxy-leghemoglobin. These opposite positions between oxy- and deoxy- leghemoglobin allow for a reduced activation energy for the reaction between leghemoglobin and oxygen. <ref>http://www.rcsb.org/pdb/explore/explore.do?structureId=2GDM<ref> | ||
== See Also == | == See Also == | ||
[[hemoglobin]] | [[hemoglobin]] | ||
[[myoglobin]] | [[myoglobin]] | ||
== References == | == References == | ||
<references/> | <references/> | ||