HEMOGLOBIN

Description

Haemoglobin, the oxygen-transport protein in the red blood cells, is a tetramer and each of the four chains contains a haeme group. It is interesting to note that the four haeme groups in haemoglobin do not operate independently. The release (and binding) of oxygen is a cooperative process, which means that the loss (uptake) of the first oxygen molecule triggers the release of the remaining three.
The current model for oxygen binding in haemoglobin and myoglobin can be explained in the following way. The deoxy form contains a high-spin Fe(II) centre, which, because of its size, does not form a plane with its four nitrogen donor atoms. Instead, it is located slightly above the plane, drawn towards the His residue. Once oxygen enters trans to the His residue, the iron centre is oxidised to a low-spin Fe³⁺ centre and O₂ is reduced to [O₂]^-. Both species contain an unpaired electron. The low-spin Fe³⁺ moves into the plane and pulls the His residue down. This affects the remaining protein chain and triggers the uptake/release of oxygen in the other three haeme groups.

Description

Hemoglobin, the major component of red blood cells, transports oxygen from the lungs to tissues throughout the body. It also carries some CO2?back to the lungs.
Hemoglobin consists of four units, each of which consists of a globin polypeptide chain bound to an iron-containing?heme?molecule. An α-chain fragment of the polypeptide?L-alanyl-L-seryl-L-leucyl-L-α-aspartyl-L-lysyl-L-phenylalanyl-L-leucyl-L-alanyl-L-seryl-L-valyl-L-seryl-L-threonyl-L-valyl-L–leucine (molar mass 1450) is shown in the figure. The average molar mass of an entire mammalian hemoglobin molecule is ≈64,500.
Here are some significant events in the history of hemoglobin discovery:

The Uses of HEMOGLOBIN

Medicine, usually called hemoglobin.

The Uses of HEMOGLOBIN

Hemoglobin is the most important respiratory protein of vertebrates by virtue of its ability to transport oxygen from the lungs to body tissues, and to facilitate the return transport of carbon dioxide. It is used as a coloring agent for pet foods, a natural source of iron for nutraceuticals, a protein source for non-ruminant animals, and as a raw material for pharmaceutical porphyrin derivative production.

The Uses of HEMOGLOBIN

Hemoglobin from bovine blood has been used in:

• standard curve generation for the quantification intraparenchymal hemorrhage and parenchymal hemorrhage in spinal cord homogenate using Drabkin′s assay, Quadrupole-Ion Mobility-Time-of-Flight mass spectrometery
• the generation of molecularly imprinted polymers (MIPs) to mimic high molecular-weight polyethylene glycol (PEG) in crystallization studies

Definition

The respiratory protein of the red blood cells, it transfers oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs. Its affinity for carbon monoxide is >200 times that for oxygen. Hemoglobin is a conjugated protein of molec

Definition

The pigment of the red blood cells that is responsible for the transport of oxygen from the lungs to the tissues. It consists of a basic protein, globin, linked with four heme groups. Heme is a complex compound containing an iron atom. The most important property of hemoglobin is its ability to combine reversibly with one molecule of oxygen per iron atom to form oxyhemoglobin, which has a bright red color. The iron is present in the divalent state (iron(II)) and this remains unchanged with the binding of oxygen. There are variations in the polypeptide chains, giving rise to different types of hemoglobins in different species. The binding of oxygen depends on the oxygen partial pressure; high pressure favors formation of oxyhemoglobin and low pressure favors release of oxygen.

Definition

One of a group ofglobular proteins occurring widely inanimals as oxygen carriers in blood.Vertebrate haemoglobin comprisestwo pairs of polypeptide chains,known as α-chains and β-chains(forming the globin protein), witheach chain folded to provide a bindingsite for a haem group. Each ofthe four haem groups binds oneoxygen molecule to form oxyhaemoglobin.Dissociation occurs inoxygen-depleted tissues: oxygen is releasedand haemoglobin is reformed.The haem groups also bind other inorganicmolecules, including carbonmonoxide (to form carboxyhaemoglobin).In vertebrates, haemoglobinis contained in the red blood cells(erythrocytes).

General Description

Native hemoglobin from bovine erythrocytes. A major oxygen-transporting component of red blood cells that is also nitric oxide scavenger. Blocks carbachol-stimulated cGMP production. This preparation contains primarily Ferric-hemoglobin and must be reduced to the ferrous form to bind molecular oxygen. Note: this preparation contains primarily ferric-hemoglobin and must be reduced to the ferrous form to bind molecular oxygen.

Biochem/physiol Actions

The Fe2+/Fe3+ balance is a physiological indicator of blood oxygenation. Deoxygenated hemoglobin accessorizes a feedback loop by reducing nitrite to NO, a vasodilator which enhances blood flow to oxygen-deprived tissues.

Purification Methods

Purify it from blood using CM-32 cellulose column chromatography. [Matsukawa et al. J Am Chem Soc 107 1108 1985.] For the purification of the  and  chains see Hill et al. Biochemical Preparations 10 55 1963. Histones (from S4A mouse lymphoma). The purification of histones uses a macroprocess column, heptafluorobutyric acid as solubilising and ion-pairing agent and an acetonitrile gradient. [McCroskey et al. Anal Biochem 163 427 1987.]