Our body consists of various trace elements and substances. Due to their constant transformation, we can live and do our job. We don’t even think about the fact that every minute of life the small particles of our body constantly work, bringing us good. Naturally, the task of each person is to constantly replenish their reserves.
Substances for the life of the body
The main substances that allow us to fully function are carbohydrates, proteins and fats. These substances in different proportions are found in almost all products, but it is important to maintain a balance of these elements, because otherwise health problems can begin. In this article we will consider the functions of proteins, how they can give the body energy.
What kind of substance is protein?
These are elements that are chains of amino acids. They have a large molecular weight, since one molecule contains several amino acids that are connected by a polypeptide bond. One unit that makes up a protein is represented by an amino acid.
This substance is an indispensable building material for the body. Almost everything in the body is built from amino acids and proteins: the supply of oxygen to a person depends on them, since hemoglobin is a protein. This substance helps maintain immunity, participates in the synthesis of hormones, so necessary for the regulation of many internal processes. It is also entrusted with an energy function, which is not characteristic of it in its entirety. Without it, it is very difficult for the body to develop and grow. But we do not need an excess of proteins. From a large number of them, fermentation processes and other negative effects on cells and organs occur.
Their main functions
Proteins perform many functions, due to this the body does not lack in the regulation of any processes, the production of new cells, immune defense, and so on. Let's consider them in more detail.
- Catalytic . Amino acids, connecting in a certain way, create enzymes that are responsible for the speed of certain reactions in the body. This is not about a dozen of enzymes involved in catalyzing. We have about several thousand of them, and they control up to 4000 reactions. All these processes are combined into one concept - metabolism. It is the proteins that determine how fast it will occur.
- Structural - with the help of certain proteins, the shape of internal cells is preserved, in the outside we have a constant shape of nails, hair and so on.
- Protective function. It lies in the fact that the proteins that make up biological fluids, substances and cells provide protection at the physical, chemical, and immune levels.
- Regulatory - there are such proteins that are not building materials of cells, do not participate in metabolism, their energy function is not characteristic, but they are involved in the regulation of processes in cells. They "monitor" the transfer of genetic information, activity and synthesis of amino acids.
- The transport function of proteins is that they transfer important and useful substances for the body with a blood stream or between cells.
- Receptor - otherwise it can be called mechanochemical. Some proteins under the influence of different signals can change their length, shrinking.
- The energy function of proteins - when protein is broken down, a certain amount of energy is released. Therefore, these substances in certain circumstances serve as its source.
In which case does the energy function of proteins occur?
Our nutrition is not always balanced so that proteins, fats and carbohydrates enter our body in exactly the amount required. Therefore, often there is a shortage or excess of certain substances.
In the case of a prolonged absence of a sufficient amount of carbohydrates and fats, the energy function of proteins comes to the fore. The body does not stop consuming energy, therefore it is the amino acid compounds that begin to supply it.
How is energy released?
Proteins are unique substances in the body. There can be thousands of variations in their structure, depending on which they are distinguished by their properties. The consumption of this substance for a long time is enormous, the same energy function of proteins leads to their breakdown, therefore, it is necessary to constantly replenish their supply. Our body helps us in this - there are many cells that synthesize protein, moreover, of a certain type and property.
The release of energy occurs with the process of protein digestion in different parts of the gastrointestinal tract. The final breakdown of amino acids occurs at the cellular level.
Conversion of proteins in the stomach
The energy function of proteins, examples of which we will consider below, begins with the breakdown of these substances in the stomach. Here the same substance comes to the rescue, but of a different structure - the
enzyme pepsin. It is active under certain conditions (when the pH is not higher than 5.0 and not lower than 2.0). By converting the secretion of the glands of the stomach, acidic gastric juice is obtained, which favorably affects the work of pepsin.
Already at this stage, the energy function of proteins begins. Pepsin is one of many enzymes that can break down complex protein collagen (the main protein in meat tissue compounds). Combining with water (hydrolysis), it forms intermediate decomposition products and a small fraction of the heat that is dissipated throughout the body, participating in energy metabolism. We can say that proteins that perform an energy function are not enzymes in their structure, since the latter only help other substances to carry out this function.
Pancreatic involvement in protein breakdown
The pancreas does not accept substances for cleavage. But it is the supplier of the necessary enzymes, so it is difficult to do without it in the digestion of proteins. It provides the digestive organs with pancreatic enzymes: proelastase, chemotrypsin, trypsin, carboxypolypeptidase.
Intestinal cleavage
Not all proteins undergo complete breakdown in the intestines, although many substances work on this. Even at the end of digestion, dipeptides and tripeptides may remain. Only some amino acids come out of this section of the gastrointestinal tract singly.
Trypsin and chemotrypsin help proteins transform into polypeptides, releasing heat when there is a lack of glucose in the body, the energy function of proteins continues to function here. We can observe examples of such a transformation every day when we consume various substances in food. After the breakdown of proteins into polypeptides, the carboxypolypeptase enzyme enters the work - it disconnects individual amino acids from the end of the formed compounds. Proelastase digests the elastic fibers of meat products and other complex substances.
Proteins that perform an energetic function go through the last stage of their cleavage in the small intestine, duodenum. There they are exposed to villi, which contain peptidases. These substances, interacting with intestinal fluid, complete the process of splitting polypeptides into a small number of amino acids. Further, the process of distribution of heat as energy from the breakdown of proteins occurs at the cellular level, and the final products of the breakdown of these complex structural substances are uric acid, urea, water and carbon dioxide. Thus, we saw where the energy function of proteins is realized. It does not have a specific location for the localization of amino acids. But it is carried out from the beginning to the complete breakdown of the protein.
Cell energy
Organelles such as mitochondria perform the energy function in the cell. There are carrier molecules on the cell membrane that drag
protein breakdown products from the molecules. In this case, energy is also released, which helps to synthesize ATP molecules and interacts with oxygen. Even at the cellular level, one can answer the question of which proteins perform an energy function. These are substances that are not involved in enzymatic work and construction, since the polypeptides that survived during cleavage are involved in the construction of body cells. But even in the future they can bring a small fraction of the energy at the cellular level with the help of mitochondria and the formed ATP molecules (a unique source of energy for all processes in the body).