Albumin
Albumins (from Latin white) are proteins soluble in the pure water , less in salt water. Their molecular weight is about 65000 g / mol, they consist of about 580 amino acids and contain no carbohydrates.
In mammals, it is a plasma protein produced by the liver. The egg white is also made up of proteids. It is found in milk , in the muscles and the blood plasma. Albumin is also present in plants, especially cereal grains. They have the ability to coagulate at about 70 C.
Summary |
Albumin is composed of a group of proteins formed from simple carbon, hydrogen, oxygen, nitrogen and a small percentage of sulfur. Albumin is coagulated by the action of heat, mineral acids, the alcohol , the ether. It is soluble in water and in low concentrated salt solutions.
Human serum albumin contains 550 amino acids and its molecular weight is 68,500 dalton. The half-life of albumin in human blood is about 21 days.
Role in vertebrates
Albumin is essential for maintaining the oncotic pressure necessary for the proper distribution of fluid between blood vessels and tissues or interstitial.
In humans
The normal range of albumin concentrations in the blood is 38 to 48 g l -1, and it usually represents about 60% of plasma proteins, all other proteins in the plasma are collectively referred to as globulins.
Functions of albumin
- Maintenance of oncotic pressure
- Transport of hormones thyroid
- Transportation of other hormones, particularly hormones soluble
- Transport of fatty acids free
- Transport of bilirubin unconjugated
- Transport of many drugs
- Transport of tryptophan Causes of impairment of albumin
- Cirrhosis of the liver (most often)
- Decreased production ( starvation , malnutrition )
- Excretion by excessive kidney : nephrotic syndrome
- Enteric protein resulting in losses
Uses
As the albumin coagulates when heated to 71 C, it is used to remove precipitates disorders and clarify the solutions in sugar refining and other processes. Albumin form insoluble compounds with many metal salts such as mercuric chloride (II), copper sulfate, silver nitrate. It is thus used as antidote against these poisons. A paste of albumin mixed with calcium hydroxide ( lime off) turns into a mass of very hard, as used cement to repair broken pottery.
It can also be used as a substitute (plasma substitute) in case of hypovolemia after a shock.
In photography, it was used in the nineteenth century to the print albumin.
In medicine
The rate of albumin in the blood called albumin. It can be lowered in certain circumstances: malnutrition, nephrotic syndrome ...
Some cases require the infusion of albumin severe hypoalbuminemia (rate <22 g l -1), nephrotic syndrome refractory jaundice nuclear infant, hypovolemic shock in children and pregnant women
bovine serum albumin
Bovine serum albumin or bovine serum albumin in English (BSA), is a source of albumin extracted from serum of ox blood. It is available in molecular biology to saturate the membrane hybridization Western blots.
References
- Pardridge W, Proud G, Transport of brain tryptophan Into From The circulating, albumin-bound pool in rats and in rabbits , Journal of Neurochemistry, 1990, 54 (3) :971-976
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