Albumin

Albumin is a protein, soluble in water and deposited in a saturated solution of ammonium sulfate, are characterized by relatively small molecular weight (15000 - 65000). In the plasma of human blood contains, on average, 43 g/l albumin; they account for 80% oncotic pressure of the blood (see Osmotic pressure). Connection albumin with metal cations called albuminates. For a number of diseases (principally, jade and other) albumin of blood pass into the urine (see Proteinuria), if the processes of synthesis cannot compensate for loss of albumin in the blood, reducing the oncotic pressure of the blood leads to swelling of tissues. Cm. also Proteins, Globulins.

Albumins (from lat. albumen, albuminis - protein) - representatives of natural proteins. Unlike globulin have the ability to dissolve in water and dilute solutions of acids, alkalis and salts. From water solutions of albumin precipitate ammonium sulfate only in the complete saturation of the solution (unlike other proteins, deposited at a lower concentration of this salt). A. deposited also alcohol, and at heating solutions to temperature 75-degree winding down.
Albumins are widely distributed in living organisms. Typical representatives A.: albumin blood serum, lactalbumin milk serum, ovalbumin eggs. In dense tissues of the human body contents A. relatively small (does not exceed 5-10% of all proteins); in the serum content of their much larger and is in the norm of 55-60% of all proteins (3,3-4,0% weight serum). A. serum are formed only in the liver, where constantly pass into the bloodstream. The amount of albumin in serum, thus, largely depends on the intensity of their biosynthesis in the liver.
Physiological role A. serum is very great: these proteins largely determine not only the properties of the serum, but a number of metabolic processes in the organism as a whole. Due to its relatively low molecular weight (65 000) they have a big influence on the osmotic and oncotic pressure of the blood and therefore the exchange of water between it and fabrics. When more or less pronounced decreases in the amount of albumin in serum ability of the latter to retain water is reduced, which leads to increased water transfer from the serum in the extracellular space of tissues, i.e. to the appearance of edema. The peculiarity of all A., primarily in serum, is the ability to form complexes with a very large number of other compounds. Almost serum albumin always contained in the form of complexes with various cations and anions, lipids, carbohydrates, pigments, hormones, etc., Thanks to the formation of these complexes are moving with the blood of many compounds from one organ to another, as well as regulation of influence of a number of substances on the vital processes of the organism.
So, for example, transport blood almost insoluble in water and clean bilirubin is possible because most of his blood forms a soluble compound with a Binding albumin and calcium ions in the form of unionised connection plays a very important role in maintaining a constant concentration in the serum calcium ions, providing a diverse impact on the functions of different organs and tissues. The same role is played by the formation of complexes A. with thyroxine, hormones crust napochechnikov, sex and so on Reduction of contents A. serum observed in so many diseases, especially chronic infectious processes, liver damage and kidney injuries bone system, after heavy operations, so to cause significant secondary changes in the exchange of various substances in the body of the patient, and put a mark on the course of the basic disease. The struggle against existing hypoalbuminemia (infusion of albumin, blood serum, an appropriate diet is therefore necessary therapeutic activity in all pathological conditions involving more or less pronounced decrease A. in the serum. Cm. also Proteins.