The basis of blood plasma are proteins contained in the range from 60 to 80 g / l, which is about four percent of all body proteins. In human blood plasma, there are about a hundred different proteins. In terms of mobility, they are divided into albumin and globulin. Initially, this division was based on the solubility method: albumin dissolves in a pure liquid, and globulins only in the presence of nitrates.
Plasma proteins
Among proteins, there is more albumin in the blood - about 45 g / l. It plays a huge role in maintaining KO pressure in the blood, and also serves as a reservoir for the reserve of amino acids.
Albumins and globulins have different abilities. The first type of protein can bind lipophilic substances. Thus, conglomerates have the opportunity to work as protein carriers of long chain fatty acids, various medications, bilirubin, vitamins, steroid hormones. Albumin is also able to bind magnesium and calcium ions.
Albumin and globulin proteins act as a transport for thyroxin, its metabolite, iodothyronine.
Protein breakdown and formation
Most plasma proteins are formed in the liver, with the exception of immunoglobulins (produced by cells of the immune system) and peptides (produced by the endocrine system).
Albumins and globulins are different in structure. All proteins, except albumin, belong to glycoproteins, the content of oligosaccharides and are attached to amino acid residues. Acetylneuraminic acid often acts as the terminal residue. If it is cleaved by neuraminidase, terminal galactose residues appear on the surface of the protein. The remains of desialized proteins are recognized, they begin to change galactoses on hepatocytes. In the liver, these already obsolete proteins are removed by endocytosis. Thus, saccharides on the surface establish the lifetime of plasma proteins, and also determine the elimination half-life, which can be up to several weeks.
In a healthy body, the concentration of albumin and globulin in the blood is maintained at a constant level. But there are situations when indicators change. This occurs with diseases of organs involved in the synthesis and catabolism of proteins. Cell damage through cytokines increases the formation of albumin, globulin, fibrinogen and some other proteins.
Electrophoresis
Proteins and other charged macromolecules can be separated by electrophoresis. Among all existing methods of division, it is especially important to distinguish electrophoresis on a carrier, namely, on a cellulose acetate film. In this case, the serum proteins move to the anode, being divided into several fractions. After dividing, the proteins are stained with a dye, which allows us to estimate the amount of protein in the colored bands.
Protein ratio
When analyzing the amount of protein in blood plasma, not only the level of albumin and globulin is determined, but also the ratio of these substances to each other is determined. Normally, there should be a 2: 1 ratio. If you deviate from these indicators, they talk about pathology.
A decrease in the ratio of albumin to globulin may indicate the following:
- decreased albumin synthesis - cirrhosis of the liver;
- low albumin levels can be observed in kidney pathologies.
An increase in the ratio of albumin to globulin can talk about such pathologies:
- hypothyroidism;
- leukemia;
- neoplasms;
- violation of the production of growth hormone.
With a decrease in globulin, autoimmune diseases, myeloma, are also detected in some cases.
Albumins help maintain osmotic pressure in the body. The test for total protein allows you to evaluate how the disease progresses, monitor oncology, detect impaired renal and hepatic function, determine the cause of edema, and evaluate the quality of nutrition.