Carbaminohemoglobin
Encyclopedia
Carbaminohemoglobin is a compound
of hemoglobin
and carbon dioxide
, and is one of the forms in which carbon dioxide exists in the blood
. When carbon dioxide binds to hemoglobin, carbaminohemoglobin is formed, lowering hemoglobin's affinity for oxygen
via the Haldane effect
. In the absence of oxygen, unbound hemoglobin molecules have a greater chance of becoming carbaminohemoglobin. (The Bohr Effect
relates to the increased affinity of de-oxygneated hemaglobin for H+
: offloading of oxygen to the tissues thus results in increased affinity of the hemaglogin for carbon dioxide
, and H+
- which the body wants to be rid of- which can then be transported to the lung for removal). The veins, which carry deoxygenated blood
back to the right atrium
of the heart
appear bluish due to the distinctive blue color of carbaminohemoglobin.(The blue color of veinous blood is not related to oxygen levels which is the common perception).
The nature of carbon dioxide's binding to hemoglobin to form carbaminohemoglobin is not always agreed upon by biochemistry texts. Four molecules of oxygen can bind to one molecule of hemoglobin. It is suggested by some that hemoglobin can also bind to four molecules of carbon dioxide. Among those who share this belief, it is generally agreed that each molecule of carbon dioxide must bind to a region on the heme
monomer
which a molecule of oxygen would not typically use. Other biochemistry texts claim that carbon dioxide does not bind to the hemoglobin tetramer
at all and can only be found floating in the cytoplasm
of the red blood cells. Research is currently being conducted in order to ascertain the truth of the matter. Haemoglobin contains the protein part called globin which combines with CO2.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
of hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, and is one of the forms in which carbon dioxide exists in the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
. When carbon dioxide binds to hemoglobin, carbaminohemoglobin is formed, lowering hemoglobin's affinity for oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
via the Haldane effect
Haldane effect
The Haldane effect is a property of hemoglobin first described by the Scottish physician John Scott Haldane. Deoxygenation of the blood increases its ability to carry carbon dioxide; this property is the Haldane effect. Conversely, oxygenated blood has a reduced capacity for carbon...
. In the absence of oxygen, unbound hemoglobin molecules have a greater chance of becoming carbaminohemoglobin. (The Bohr Effect
Bohr effect
Bohr effect is a property of hemoglobin first described in 1904 by the Danish physiologist Christian Bohr , which states that an increasing concentration of protons and/or carbon dioxide will reduce the oxygen affinity of hemoglobin...
relates to the increased affinity of de-oxygneated hemaglobin for H+
H+
H+ or h+ may refer to:* H+ , a web series produced by John Cabrera* Hydron , H+* Electron hole, h+* H * Transhumanism, H+, h+...
: offloading of oxygen to the tissues thus results in increased affinity of the hemaglogin for carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, and H+
H+
H+ or h+ may refer to:* H+ , a web series produced by John Cabrera* Hydron , H+* Electron hole, h+* H * Transhumanism, H+, h+...
- which the body wants to be rid of- which can then be transported to the lung for removal). The veins, which carry deoxygenated blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
back to the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...
of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
appear bluish due to the distinctive blue color of carbaminohemoglobin.(The blue color of veinous blood is not related to oxygen levels which is the common perception).
The nature of carbon dioxide's binding to hemoglobin to form carbaminohemoglobin is not always agreed upon by biochemistry texts. Four molecules of oxygen can bind to one molecule of hemoglobin. It is suggested by some that hemoglobin can also bind to four molecules of carbon dioxide. Among those who share this belief, it is generally agreed that each molecule of carbon dioxide must bind to a region on the heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...
monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
which a molecule of oxygen would not typically use. Other biochemistry texts claim that carbon dioxide does not bind to the hemoglobin tetramer
Tetramer
A tetramer is a protein with four subunits . There are homotetramers such as glutathione S-transferase or single-strand binding protein, dimers of hetero-dimers such as hemoglobin , and heterotetramers, where each subunit is different.-Subunit interactions in tetramers:The interactions between...
at all and can only be found floating in the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
of the red blood cells. Research is currently being conducted in order to ascertain the truth of the matter. Haemoglobin contains the protein part called globin which combines with CO2.