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Oxidation and reduction pathways of methemoglobin and hemoglobin. Published by N. De Crem et al., 2022. In living organisms, because methemoglobin (MetHb) is unable to bind oxygen, it must be reduced to hemoglobin (Hb) through the action of the soluble isoform of cytochrome b5 reductase.
Leghemoglobin (also leghaemoglobin or legoglobin) is an oxygen-carrying phytoglobin found in the nitrogen-fixing root nodules of leguminous plants. It is produced by these plants in response to the roots being colonized by nitrogen-fixing bacteria, termed rhizobia, as part of the symbiotic interaction between plant and bacterium: roots not colonized by Rhizobium do not synthesise leghemoglobin.
Phytoglobins are globular plant (algae and land plant) proteins classified into the globin superfamily, which contain a heme, i.e. protoporphyrin IX -Fe, prosthetic group. The earliest known phytoglobins are leghemoglobins , discovered in 1939 by Kubo after spectroscopic and chemical analysis of the red pigment of soybean root nodules . [ 1 ]
In plants, algae, bacteria (except for the α-proteobacteria group) and archaea, it is produced from glutamic acid via glutamyl-tRNA and glutamate-1-semialdehyde. The enzymes involved in this pathway are glutamyl-tRNA synthetase, glutamyl-tRNA reductase, and glutamate-1-semialdehyde 2,1-aminomutase. This pathway is known as the C5 or Beale pathway.
For example, the ability of hemoglobin to effectively deliver oxygen to tissues is due to specific amino acid residues located near the heme molecule. [13] Hemoglobin reversibly binds to oxygen in the lungs when the pH is high, and the carbon dioxide concentration is low. When the situation is reversed (low pH and high carbon dioxide ...
This pathway has been demonstrated in Chloroflexus, a nonsulfur photosynthetic bacterium; however, other studies suggest that 3-hydroxypropionate bicycle is used by several chemotrophic archaea. [ 1 ] [ 4 ] T In E. coli 3-hydroxypropionate bicycle has been studied and found to be insensitive to oxygen.
In biochemistry, the Luebering–Rapoport pathway (also called the Luebering–Rapoport shunt) is a metabolic pathway in mature erythrocytes involving the formation of 2,3-bisphosphoglycerate (2,3-BPG), which regulates oxygen release from hemoglobin and delivery to tissues. 2,3-BPG, the reaction product of the Luebering–Rapoport pathway was first described and isolated in 1925 by the ...
A NO mutant resulted in inhibition of vacuolation but when GA was later added the process was active again leading to the belief that NO is prior to GA in the pathway. NO may also lead to the decrease in sensitivity of Abscisic acid (ABA), a plant hormone largely responsible for seed dormancy. [6] The balance between GA and ABA is important.