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The structure of cytochrome b5 reductase, the enzyme that converts methemoglobin to hemoglobin. [1]Methemoglobin (British: methaemoglobin, shortened MetHb) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe 3+ state, not the Fe 2+ of normal hemoglobin.
Cytochrome b5 reductase is a prevalent topic in research and clinical tests to understand the additional functions of the enzyme in other metabolic pathways in the body. Mice and flies are common model organisms used to test for the relationship of cytochrome b5 reductase with the overall health of living organisms.
Normally, methemoglobin levels are <1%, as measured by the CO-oximetry test. Elevated levels of methemoglobin in the blood are caused when the mechanisms that defend against oxidative stress within the red blood cell are overwhelmed and the oxygen carrying ferrous ion (Fe 2+) of the heme group of the hemoglobin molecule is oxidized to the ...
It's also heavily involved in many oxidation and reduction reactions, such as the reduction of methemoglobin to hemoglobin. [10] Of the two forms of NADH-cytochrome b5 reductase, the membrane-bound form exists mainly on the cytoplasmic side of the endoplasmic reticulum and functions in desaturation and elongation of fatty acids , in cholesterol ...
NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) is a membrane-bound enzyme complex that faces the extracellular space. It can be found in the plasma membrane as well as in the membranes of phagosomes used by neutrophil white blood cells to engulf microorganisms.
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 ...
Hemoglobin M disease is a rare form of hemoglobinopathy, characterized by the presence of hemoglobin M (HbM) and elevated methemoglobin (metHb) level in blood. [1] HbM is an altered form of hemoglobin (Hb) due to point mutation occurring in globin-encoding genes, mostly involving tyrosine substitution for proximal (F8) or distal (E7) histidine residues. [2]
In living muscle, the concentration of metmyoglobin is vanishingly small, due to the presence of the enzyme metmyoglobin reductase, which, in the presence of the cofactor NADH and the coenzyme cytochrome b4 converts the Fe 3+ in the heme prosthetic group of metmyoglobin back to the Fe 2+ of normal myoglobin.