How is the process of protein breakdown in our body? These organic substances are the main biological material for the formation and growth of living cells. Numerous functions that protein molecules perform in a living organism cannot be compensated by other elements and substances, since it is in polypeptides that essential amino acids are found. The main purpose of proteins is their participation in the replication of RNA and DNA molecules.
The significance of the process of decay of protein molecules
It is impossible to imagine a full life without protein compounds. They are the main material for building new cells, organs, and various tissues. Protein breakdown products are amino acids. They are necessary for a living being to synthesize new protein molecules specific to a given organism. Amino acids obtained from the breakdown of protein molecules are required for the formation of many hormones, enzymes,hemoglobin, other substances that perform important functions in the body.
Essential amino acids, which 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.
Mechanism of protein breakdown process
Let's consider this phenomenon in more detail. The process of protein breakdown is associated with biochemical reactions occurring 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 comes 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. Missing amino acids are called essential, they can only enter the body with food. For complete assimilation of food protein, amino acids must be contained in it in a strictly defined ratio. It is individual for each living organism. With a lack of one of the amino acids, during the breakdown of protein molecules,the participation of other amino acids in the synthesis of a protein specific to a living organism.
Features of decay products
The body systematically lacks or lacks protein. The end products of protein breakdown are the material for the vital activity of a living organism. World He alth Organization experts have proven 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 from the tissues worse, hungry edema appears.
Process essence
Protein hydrolysis occurs under the influence of proteolytic enzymes (biological catalysts). It proceeds at insignificant temperatures. All enzymes of the gastrointestinal tract act on the peptide bond, but each selects "their" bonds that form certain amino acids.
For example, pepsin quickly destroys bonds between serine and alanine residues, while trypsin “recognizes” lysine and arginine groups.
In the stomach, destruction is carried out under the influence of the acidic environment of gastric juice, as well as due to the action of pepsin. It breaks internal bonds in the protein molecule, the interaction product will be large fragments of the protein polymer - peptones. They go to the duodenum, where they are subsequently converted under the influence of enzymes: chymoptrypsin, trypsin, peptidases. Protein degradation is associated with the destruction of peptide bonds, which are affected by the enzyme. After treatment with chymotrypsinhalf of the peptide bonds are hydrolyzed.
Subsequent protein breakdown is carried out in the small intestine under the influence of peptidase enzymes.
Carboxypeptidases are able to cleave 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, splitting dipeptides into free amino acids.
Due to the joint action of a group of enzymes in different parts of the gastrointestinal tract, food protein is completely broken down into free amino acids.
They are absorbed through the walls of small capillaries and end up in the blood. Most of these amino acids are distributed throughout the living organism, enter the organs and tissues. In cells, they are used to build new proteins that are specific to a given organism. This is used by doctors when performing a blood transfusion procedure so that there is no rejection of the donor material.
Protein quality
In a living organism, the processes of renewal and destruction of cells, as well as extracellular substance, which contains protein molecules, are constantly, albeit at different speeds.
The process of protein breakdown is accompanied by the release of a significant amount of energy.
Protein-free diet 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, in order to compensate for the protein that has decayed in the body, it is necessary that with foodcame 1 g of the amino acid methionine. Proteins of hair, feathers, wool contain a complete amino acid composition. By 1915, it was found that the protein zein, which is part of corn, does not stimulate cell growth. When the amino acid tryptophan is added to it, living organisms fully grow.
Proteins of different organs, tissues, organisms have significant differences in molecular weight, charge, amino acid composition, and other parameters. The protein of one organism is foreign to another. The breakdown of protein leads to the formation of amino acids that are needed for nutrition.
