How does the process of protein breakdown in our body? These organic substances are the main biological material for the formation and growth of living cells. The numerous functions that protein molecules perform in a living organism cannot be compensated for by other elements and substances, since it is the polypeptides that contain essential amino acids. The main purpose of proteins is their participation in the replication of RNA and DNA molecules.
The significance of the breakdown of protein molecules
It is impossible to imagine a full life without protein compounds. They are the main material for building new cells, organs, various tissues. The breakdown products of proteins are amino acids. They are necessary for a living being to synthesize new protein molecules specific for a given organism. Amino acids obtained by the breakdown of protein molecules are required for the formation of many hormones, enzymes, hemoglobin, and other substances that perform important functions in the body.
Essential amino acids that enter the body only with food are formed during the hydrolysis of protein molecules. The process of forming a new protein from amino acid residues allows the body to receive energy and building material for the synthesis of new cells.
The mechanism of protein breakdown
Let us consider this phenomenon in more detail. The process of protein breakdown is associated with biochemical reactions that occur in the cavity of the small intestine. Diseases of the small intestine and pancreas adversely affect this process. The breakdown of one kilogram of protein should be accompanied by the release of 17.6 kJ of energy. After the polypeptide breaks down into amino acids, the process does not stop. Next is the formation of inorganic products: carbon dioxide, ammonia, hydrogen sulfide, water.
Features
The breakdown of proteins in the body is a process that provides the body with the necessary amount of energy. These organic compounds contain more than twenty amino acids, but only eight of them can be synthesized inside the body. The missing amino acids are called indispensable, they can enter the body only with food. For complete assimilation of food protein, amino acids must be contained in it in a strictly defined ratio. It is individual for every living organism. When one of the amino acids is deficient, the breakdown of protein molecules disrupts the participation of other amino acids in the synthesis of a protein specific to a living organism.
Features of decay products
The body is systematically deficient or deficient in protein. The final products of protein breakdown - a material for the life of a living organism. Experts from the World Health Organization have shown that protein deficiency is a phenomenon characteristic of underdeveloped countries. With a decrease in the amount of protein in the blood, the osmotic pressure of the blood decreases, it takes water worse from the tissues, and hungry edema appears .
Process essence
Protein hydrolysis occurs under the influence of proteolytic enzymes (biological catalysts). It occurs at insignificant temperatures. All enzymes of the gastrointestinal tract affect the peptide bond, but each one selects “their” bonds, which form certain amino acids.
For example, pepsin quickly destroys the bonds between serine and alanine residues, and trypsin “recognizes” lysine and arginine groups.
In the stomach, destruction is carried out under the influence of the acidic environment of the gastric juice, as well as due to the effects of pepsin. It breaks internal bonds in a protein molecule; large fragments of a protein polymer — peptones — will be the interaction product. They go to the duodenum, where they are subsequently converted under the influence of enzymes: chymoprypsin, trypsin, peptidases. Protein breakdown is associated with the destruction of peptide bonds that are affected by the enzyme. After treatment with chymotrypsin, more than half of the peptide bonds are hydrolyzed.
Subsequent protein breakdown occurs in the small intestine under the influence of peptidase enzymes.
Carboxypeptidases are capable of cleaving amino acids from residues of the protein structure from the carboxyl end, and aminopeptidases act on the side where the free amino group is present, cleaving dipeptides to free amino acids.
Thanks to the combined action of a group of enzymes in different parts of the gastrointestinal tract, the complete breakdown of food protein into free amino acids occurs.
They are absorbed through the walls of small capillaries, appear in the blood. Most of these amino acids are distributed throughout the living organism and enter organs and tissues. In the cells from them, the construction of new proteins that are specific for a given organism occurs. This is used by doctors during the blood transfusion procedure so that there is no rejection of donor material.
Protein quality
In a living organism, processes of renewal and destruction of cells, as well as extracellular substance, which contains protein molecules, are constantly carried out, albeit at different speeds.
The process of protein breakdown is accompanied by the release of a significant amount of energy.
Protein-free nutrition leads to death, as the body does not receive the necessary amino acids. It is important not only the amount of protein that is consumed with food, but also their quality. For example, to compensate for the protein disintegrated in the body, it is necessary that 1 g of the amino acid methionine come with food. Proteins of hair, feathers, wool contain a complete amino acid composition. By 1915, it was found that the zein protein, which is part of corn, does not stimulate cell growth. When tryptophan amino acids are added to it, living organisms fully grow.
Proteins of different organs, tissues, organisms have significant differences in molecular weight, charge, amino acid composition, as well as other parameters. The protein of one organism is alien to another. The breakdown of protein leads to the formation of amino acids that are needed for nutrition.