References




Comments

Post a Comment

Popular posts from this blog

Iron's oxidation state in oxyhemoglobin

Image
Assigning oxygenated hemoglobin's oxidation state is difficult because oxyhemoglobin (Hb-O 2 ), by experimental measurement, is diamagnetic (no net unpaired electrons), yet the lowest-energy (ground-state) electron configurations in both oxygen and iron are paramagnetic (suggesting at least one unpaired electron in the complex). The lowest-energy form of oxygen, and the lowest energy forms of the relevant oxidation states of iron, are these: Triplet oxygen, the lowest-energy molecular oxygen species, has two unpaired electrons in antibonding π* molecular orbitals. Iron(II) tends to exist in a high-spin 3d6 configuration with four unpaired electrons. Iron(III) (3d5) has an odd number of electrons, and thus must have one or more unpaired electrons, in any energy state. All of these structures are paramagnetic (have unpaired electrons), not diamagnetic. Thus, a non-intuitive (e.g., a higher-energy for at least one species) distribution of electrons in the combination of iron and oxy...
Read more

Genetics

Image
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 any polypeptide created by a cell is in turn determined by the stretches of DNA called genes. In all 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 present) is coded for by the genes, HBA1 , HBA2 , and HBB . 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 most common hemoglobin sequences in humans, bonobos and chimpanzees are completely identical, without even single amino acid difference in either the alpha or the beta globin protein chains. Whereas the human and gorilla hemoglobin differ in one...
Read more

Hemoglobin

Image
Hemoglobin (American English) or haemoglobin (British English) (Greek αἷμα (haîma, “blood”) + -in) + -o- + globulin (from Latin globus (“ball, sphere”) + -in) ( / ˈ h iː m ə ˌ ɡ l oʊ b ɪ n , ˈ h ɛ -, - m oʊ -/ ), abbreviated Hb or Hgb , is the iron-containing oxygen-transport metalloprotein in the red blood cells (erythrocytes) of almost all vertebrates (the exception being the fish family Channichthyidae) as well as the tissues of some invertebrates. Hemoglobin in blood carries oxygen from the lungs or gills to the rest of the body (i.e. the tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power the functions of the organism in the process called metabolism. A healthy individual has 12 to 20 grams of hemoglobin in every 100 ml of blood. In mammals, the protein makes up about 96% of the red blood cells' dry content (by weight), and around 35% of the total content (including water). Hemoglobin has an oxygen-binding capacity of 1.34 mL O...
Read more