Proteins: what they are and how they influence the functioning of the body

These are the main characteristics of proteins as an element of nutrition.

Proteins are biomolecules consisting mainly of carbon, hydrogen, oxygen and nitrogen.. These are not their only components, as certain protein structures may contain sulfur, phosphorus, iron, magnesium, copper and other chemical elements.

From a physiological point of view, proteins are the main components of the cell, which is why they are needed for tissue repair, growth, cell division and many other functions related to the physical structure of living beings.

For this reason, it is not surprising that 10 to 15% of the diet of any human being should be composed of proteins. Fortunately, these macromolecules essential for life are found in multiple foods: salmon, eggs, milk, legumes, beef and a long list of other foods.

Because of the physical and nutritional importance of these biomolecules, we find it necessary to investigate the morphology, properties and necessary intake of these macromolecules. the morphology, properties and necessary intake of proteins.. Continue with us on this journey through various biochemical concepts, as we assure you that some of the data in the following lines will surprise you.

What are the characteristics of proteins?

To whet your appetite, we are going to present you with a series of facts that frame the world of proteins on a more tangible and objective plane. Let's get started:

• Proteins represent approximately 50% of the dry weight of the tissues of living beings.
• An adult individual needs to ingest one gram of protein per day for every kilogram of weight.
• The amino acids that make up proteins are encoded in the standard genetic code, common to all living beings.
• One gram of protein provides 4 kilocalories of energy.
• The human body has about 100,000 types of proteins, all of which are necessary for the performance of vital functions.

As we can see, proteins are governed by a universal language (the genetic code) and make up the various structures of all living things. make up the various structures of all living things around us.. Even so, we have introduced a term that we have to explain in depth, because we cannot understand the protein structure without it: it is time to talk about the amino acid.

Amino acids and their importance

An amino acid is defined as each one of the basic units that make up proteins.. Its chemical structure is based on a central carbon molecule, an amino group, a carboxyl group, a hydrogen atom and a variable chemical radical. Thus, we are dealing with a kind of chemical "cross" with a tetrahedral structure in the three-dimensional plane.

There are 20 different amino acids, which are joined in various orders by peptide bonds to form the proteins (polypeptide chains) present in nature. Summarizing this terminological conglomerate in a basic simile, it is as if we were using the same pieces of a puzzle to create a different picture each time: the results are very different from each other due to the order of the individual components, but the basic material is the same. In this case, it is clear that the order does alter the product.

We can distinguish two types of amino acids: essential and non-essential.. The essential ones are those that cannot be synthesized by the organism and therefore must be ingested through the diet. It should be noted that the "essentiality" of each one of them depends on the taxon of living being in which we look at, since the different metabolic pathways of the species mean that some need certain compounds that others do not.

On the other hand we have the non-essential amino acids, those that we can synthesize inside our organism (mainly in the liver) from intermediates by transamination, and that therefore are not strictly necessary in the diet. In last place are the conditionally essential amino acids, that is, those that are required in the daily intake in certain frameworks and specific situations.

Finally, and after this very brief review of the world of amino acids, it is necessary to emphasize that the nutritional quality of a protein is codified by the number of essential amino acids present in its chemical structure, in addition to the digestibility of its components and the proportion retained by the body.The nutritional quality of a protein is codified by the number of essential amino acids present in its chemical structure, as well as the digestibility of its components and the proportion retained by the body.

Protein structure

Describing the structural complexity of proteins as we have done with amino acids is a practically impossible task, since the writing space is finite and there is a lot of ground to cover. Suffice it to know that all proteins have the same central chemical skeleton, i.e. a linear chain of various amino acids.. This is called the "primary structure", and it is what mainly determines the nature and function of the protein in the organism.

It gets much more complicated, because due to the folding of the macromolecule, its three-dimensional arrangement and many other factors, proteins also have tertiary, secondary and quaternary structure.

Functions

All proteins perform essential functions for cellular development and maintenance.However, we can summarize the tasks of these biomolecules in the following points:

• Catalysis: enzymes are commonly proteins, so we can say that these are in charge of carrying out multiple chemical reactions in our body.
• Regulators: Hormones are proteins. They are responsible for maintaining the balance of our body, among many other behavioral and physical functions.
• Protective: immunoglobulins (antibodies) are of a protein nature, which is why their immunological function is vital.
• Structural: collagen, tubulin, keratin and many other protein compounds make up the physical structures that characterize us as organisms.

We could go on listing functions for days, since some proteins (by themselves or in association with other compounds) are transporters of substances in the bloodstream, have motor functions, give coloration to living beings, are energy reserves and many other functions.. In short: virtually all Biological processes require the presence of proteins.

Proteins and nutrition

The World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) indicate that 10 to 15 % of an individual's daily energy requirement should come directly from protein.. This value varies depending on the needs and requirements of the person in question, for example, an athlete with high muscle development may need to increase this intake to 35%.

But beware: medical organizations such as the Mayo Clinic warn us that consuming more than two grams of protein per kilogram of weight of the individual begins to be excessive, which can translate into long-term liver and kidney problems. In any case, this type of pathologies should not worry the general population, since consuming such a high percentage of protein is practically impossible unless one resorts to supplements.

Contrary to what certain sectors of the population believe, not only meat and animal by-products contain protein.. For example, 100 grams of lentils have 9 grams of pure protein. It is true that meat has a higher proportion (25 grams per 100 grams of steak), but it is possible to obtain all the necessary protein intake without resorting to meat products.

Protein is present in a wide range of foods, whether of animal or vegetable origin: fish, red meat, chicken, turkey, eggs, milk, nuts, soy, oats and many other foods. Thus, the source and modulation of the diet based on protein intake depends entirely on individual values and needs..

Summary

As we have seen, there is enough information available on proteins to write several books. From a biological point of view, they represent the majority of the organic components of the tissues of living beings and fulfill a series of countless functions in our organism. They also have a characteristic structure based on amino acids, universal compounds that encode their functionality and nature according to their arrangement in the linear chain.

Finally, we have also shown you the importance of protein intake in the human diet and which foods are rich in it. Of course, we are facing a biomolecule and macronutrient (along with fats and carbohydrates) without which we could not live.

Bibliographic references:

• Are you consuming too much protein? Mayoclinic. Retrieved October 13 from https://newsnetwork.mayoclinic.org/discussion/esta-consumiendo-demasiada-proteina/.
• Some facts about protein, radychildren.org (San Diego Hospital). Retrieved October 13 from https://www.rchsd.org/health-articles/algunos-datos-sobre-las-protenas/
• Guidelines on nutrition labeling (FAO). Retrieved October 13 from http://www.fao.org/ag/humannutrition/33311-065a023f960ba72b7291fb0bc07f36a3a.pdf
• FAO and WHO present expert report on diet, nutrition and chronic disease prevention (WHO). Retrieved October 13 from https://www.who.int/mediacentre/news/releases/2003/pr32/es/#:~:text=The%20recommended%20diet%20of%20prote%20prote%20C3%ADnas%20and%20the%20control%20of%20weight.
• Proteins, Manual of Nutrition and Dietetics of the Complutense University of Madrid. Retrieved October 13 from https://www.ucm.es/data/cont/docs/458-2013-07-24-cap-5-proteinas.pdf.
• Seguí, M. (2011). Structure and properties of proteins.
• Suárez López, M. M., Kizlansky, A., & López, L. B. (2006). Evaluation of protein quality in foods by calculating the digestibility-corrected amino acid score. Hospital Nutrition, 21(1), 47-51.