Скачать с ютуб Hemoglobin | Structure and Types в хорошем качестве

Hemoglobin | Structure and Types

Erythrocytes Video Link :    • Erythrocytes | Structure and Diseases   Hemoglobin (also spelled haemoglobin[a], abbreviated Hb or Hgb), is the iron-containing oxygen-transport protein present in red blood cells (erythrocytes) of almost all vertebrates. emoglobin in blood carries oxygen from the respiratory organs (lungs or gills) to the other tissues of the body, where it releases the oxygen to enable aerobic respiration which powers the animal's metabolism. Hemoglobin consists of protein subunits (globin molecules), which are polypeptides, long folded chains of specific amino acids which determine the protein's chemical properties and function. The amino acid sequence of any polypeptide is translated from a segment of DNA, the corresponding gene. 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 in adults) is coded by genes HBA1, HBA2, and HBB.[29] Subunits alpha 1 and alpha 2 are respectively coded by genes HBA1 and HBA2 close together on chromosome 16, while subunit beta is coded by gene HBB on chromosome 11. The amino acid sequences of the globin subunits usually differ between species, with the difference growing with evolutionary distance. For example, the most common hemoglobin sequences in humans, bonobos and chimpanzees are completely identical, with exactly the same alpha and beta globin protein chains.[30][31][32] Human and gorilla hemoglobin differ in one amino acid in both alpha and beta chains, and these differences grow larger between less closely related species. Hemoglobin has a quaternary structure characteristic of many multi-subunit globular proteins. Most of the amino acids in hemoglobin form alpha helices, and these helices are connected by short non-helical segments. Hydrogen bonds stabilize the helical sections inside this protein, causing attractions within the molecule, which then causes each polypeptide chain to fold into a specific shape. Hemoglobin's quaternary structure comes from its four subunits in roughly a tetrahedral arrangement.[42] In most vertebrates, the hemoglobin molecule is an assembly of four globular protein subunits. Each subunit is composed of a protein chain tightly associated with a non-protein prosthetic heme group. Each protein chain arranges into a set of alpha-helix structural segments connected together in a globin fold arrangement. Such a name is given because this arrangement is the same folding motif used in other heme/globin proteins such as myoglobin.[44][45] This folding pattern contains a pocket that strongly binds the heme group.