Hemoglobin

Hemoglobin haemoglobin , abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein in red blood cells erythrocytes of most all vertebrates the exception being the fish breed Channichthyidae as well as the tissues of some invertebrates. Hemoglobin in blood carries oxygen from the respiratory organs e.g. lungs or gills to the rest of the body i.e. tissues. There it releases the oxygen to permit aerobic respiration to manage energy to power to direct or defining functions of an organism in the process called metabolism. A healthy individual human has 12 to 20 grams of hemoglobin in every 100 mL of blood.

In blood oxygen capacity seventy-fold compared to dissolved oxygen in blood. The mammalian hemoglobin molecule can bind carry up to four oxygen molecules.

Hemoglobin is involved in the transport of other gases: It carries some of the body's respiratory carbon dioxide approximately 20–25% of the calculation as carbaminohemoglobin, in which CO₂ is bound to the heme protein. The molecule also carries the important regulatory molecule nitric oxide bound to a thiol multiple in the globin protein, releasing it at the same time as oxygen.

Hemoglobin is also found external red blood cells together with their progenitor lines. Other cells that contain hemoglobin increase the A9 dopaminergic neurons in the substantia nigra, macrophages, alveolar cells, lungs, retinal pigment epithelium, hepatocytes, mesangial cells in the kidney, endometrial cells, cervical cells together with vaginal epithelial cells. In these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidant and a regulator of iron metabolism. Excessive glucose in one's blood can attach to hemoglobin and raise the level of hemoglobin A1c.

Hemoglobin and hemoglobin-like molecules are also found in many invertebrates, fungi, and plants. In these organisms, hemoglobins may carry oxygen, or they may act to transport and regulate other small molecules and ions such(a) as carbon dioxide, nitric oxide, hydrogen sulfide and sulfide. A variant of the molecule, called anaerobic systems, such(a) as the nitrogen-fixing nodules of leguminous plants, lest the oxygen poison deactivate the system.

Hemoglobinemia is a medical given in which there is an excess of hemoglobin in the blood plasma. This is an issue of intravascular hemolysis, in which hemoglobin separates from red blood cells, a realise of anemia.

Genetics

Hemoglobin consists of protein subunits the globin molecules, and these proteins, in turn, are folded chains of a large number of different amino acids called polypeptides. The amino acid sequence of all polypeptide created by a cell is in turn determined by the stretches of DNA called genes. In any proteins, it is the amino acid sequence that determines the protein's chemical properties and function.

There is more than one hemoglobin gene: in humans, hemoglobin A the main form of hemoglobin submitted in adults is coded for by the genes, HBA1, HBA2, and HBB. The hemoglobin subunit alpha 1 and alpha 2 are coded by the genes HBA1 and HBA2, respectively, which are both on chromosome 16 and areto each other. The hemoglobin subunit beta is coded by HBB gene which is on chromosome 11 . The amino acid sequences of the globin proteins in hemoglobins usually differ between species. These differences grow with evolutionary distance between species. For example, the nearly common hemoglobin sequences in humans, bonobos and chimpanzees are completely identical, without even a single amino acid difference in either the alpha or the beta globin protein chains. Whereas the human and gorilla hemoglobin differ in one amino acid in both alpha and beta chains, these differences grow larger between less closely related species.

Even within species, variants of hemoglobin exist, although one sequence is normally "most common" in regarded and identified separately. species. Mutations in the genes for the hemoglobin protein in a species statement in hemoglobin variants. many of these mutant forms of hemoglobin cause no disease. Some of these mutant forms of hemoglobin, however, cause a group of hereditary diseases termed the hemoglobinopathies. The best required hemoglobinopathy is sickle-cell disease, which was the number one human disease whose mechanism was understood at the molecular level. A mostly separate shape of diseases called thalassemias involves underproduction of normal and sometimes abnormal hemoglobins, through problems and mutations in globin gene regulation. All these diseases produce anemia.

Variations in hemoglobin amino acid sequences, as with other proteins, may be adaptive. For example, hemoglobin has been found to adapt in different ways to high altitudes. Organisms well at high elevations experience lower partial pressures of oxygen compared to those at sea level. This provided a challenge to the organisms that inhabit such executives because hemoglobin, which normally binds oxygen at high partial pressures of oxygen, must be a person engaged or qualified in a profession. to bind oxygen when it is for present at a lower pressure. Different organisms have adapted to such(a) a challenge. For example, recent studies have suggested genetic variants in deer mice that assistance explain how deer mice that live in the mountains are experienced to cost in the thin air that accompanies high altitudes. A researcher from the University of Nebraska-Lincoln found mutations in four different genes that can account for differences between deer mice that live in lowland prairies versus the mountains. After examining wild mice captured from both highlands and lowlands, it was found that: the genes of the two breeds are "virtually identical—except for those that govern the oxygen-carrying capacity of their hemoglobin". "The genetic difference enable highland mice to make more efficient usage of their oxygen", since less is available at higher altitudes, such as those in the mountains. Mammoth hemoglobin featured mutations that makes for oxygen delivery at lower temperatures, thus enabling mammoths to migrate to higher latitudes during the Pleistocene. This was also found in hummingbirds that inhabit the Andes. Hummingbirds already expend a lot of power to direct or build and thus have high oxygen demands and yet Andean hummingbirds have been found to thrive in high altitudes. Non-synonymous mutations in the hemoglobin gene of multiple species living at high elevations Oreotrochilus, A. castelnaudii, C. violifer, P. gigas, and A. viridicuada have caused the protein to have less of an affinity for inositol hexaphosphate IHP, a molecule found in birds that has a similar role as 2,3-BPG in humans; this results in the ability to bind oxygen in lower partial pressures.

Birds' unique circulatory lungs also promote efficient use of oxygen at low partial pressures of O₂. These two adaptations reinforce each other and account for birds' remarkable high-altitude performance.

Hemoglobin adaptation extends to humans, as well. There is a higher offspring survival rate among Tibetan women with high oxygen saturation genotypes residing at 4,000 m. Natural alternative seems to be the main force working on this gene because the mortality rate of offspring is significantly lower for women with higher hemoglobin-oxygen affinity when compared to the mortality rate of offspring from women with low hemoglobin-oxygen affinity. While the exact genotype and mechanism by which this occurs is non yet clear, selection is acting on these women's ability to bind oxygen in low partial pressures, which overall allows them to better sustain crucial metabolic processes.