Living beings are composed of many different chemical substances (between 25 and 30), but 96% of the mass of most cells is made up of the following essential bioelements: carbon (C), hydrogen (H), oxygen ( O), sulfur (S), nitrogen (N) and phosphorus (P), which are much more abundant in living organic matter than in the rest of the elements of the Earth’s crust.
Proteins, macromolecules formed from linear chains of amino acids, are the basis of all living tissue, since they represent 80% of the dehydrated cellular protoplasm and 50% of the dry weight of all tissue associations in the body. Genes, enclosed in the nucleus in the form of chromosomes, encode the synthesis of specific proteins through nucleic acid sequences. Thanks to the mechanisms of transcription and translation, the genetic code becomes the functional elements that shape our body.
About 500 types of amino acids have been identified, but only 20 are part of the proteins of the human body, that is, they are encoded at the genetic level. In any case, the number of linked amino acids, the order in which each of them is placed, the three-dimensional conformation of the chains and the prosthetic (non-protein) groups provide an unfathomable variety of proteins in just one organism. Today we tell you everything about one of the most important: collagen
Collagen is the most abundant fibrous protein in the extracellular matrix and connective tissue It is one of the main components of the skin and bones and therefore covers approximately 25% of the protein mass of the human organism. It is also found in tendons, ligaments and cartilage. Depending on the degree of mineralization, collagen can be rigid, malleable, or fall somewhere in between.
Collagen is a protein and, therefore, is made up of amino acids. Amino acids are the basic protein subunits that are joined together by peptide bonds: when 2 to 10 are associated the compound is called a peptide, from 10 to 50 it is a polypeptide and from 50 onwards it is a protein. The genetic code is universal, which means that the information that encodes the placement of an amino acid when assembling a protein is the same in all living beings.
In general, this very special protein is found in the form of a triple helix, composed of two identical polypeptide chains α1 and one that differs slightly from them (α2). The most common collagen repeat pattern is as follows:
Glycine-proline-X // glycine-X-hydroxyproline
It should be noted that “X” is any amino acid that is not any of the 3 mentioned. Due to this conformation, collagen It is rich in the amino acids glycine, proline and hydroxyproline Above all, this last amino acid differentiates it from the rest of the protein elements, since it is not usual for a protein to have so much hydroxyproline in its polypeptide skeleton. For example, human collagen has 329 units of glycine, 126 of proline and 95 of hydroxyproline per 1000 amino acid residues.
types of collagen
We have talked about collagen as a unique and invariable protein, but nothing could be further from the truth. Depending on the type of chains they present, their arrangement, their location and the interrelation with other elements, various types of collagen can be detected Among them, we highlight the following:
We could continue citing examples, since we left collagens IV, VI, VII, VIII, IX, XI, XII and others in the pipeline, since there are a total of 22. In any case, the idea is clear: this protein It is made up of different types of chains and, depending on their arrangement (fibers, networks, hexagonal networks, associated with fibers or transmembrane), several types of collagen can be counted with different functionalities.
Common generalities
It can be very confusing to engage in such specific terminology, as it is easy to get lost between chains, polypeptides and synthesis zones. Therefore, we collect A series of basic ideas regarding collagen in the following list:
What is the function of collagen?
Collagen is uone of the main parts of connective tissue, as it is synthesized and secreted by fibroblasts, very abundant in these tissue associations. As its name indicates (connective, connection), collagen and the rest of the cell bodies associated with these tissues have the purpose of connecting the body structures and keeping them together, thus giving rise to the three-dimensional shape of the human body.
collagen It has great tensile strength, which makes it the main candidate to form part of fascia, cartilage, ligaments, skin, tendons and bones Furthermore, along with keratin and elastin, it is responsible for the plasticity and deformation capacity of the skin. Beyond type I, collagen XVII is another of the most important, since it is the joining point between the dermis and the epidermis.
Furthermore, it should be noted that collagen accompanies us beyond the locomotor system and the skin, as it is also part of key structures during fetal development, blood vessels, intervertebral discs and even the cornea. Without going any further, the stroma, the thickest part of the ocular cornea, is made up of about 200 interconnected collagen fibers. Without this protein, seeing properly would be impossible.
For all these reasons, It is not surprising that many of the mutations associated with the collagen-coding genes translate into serious pathologies Additionally, because mutations in one chain can affect healthy collagen fibers, these mutations are considered dominant (they are expressed even if one of the two copies of the gene is healthy). Ankylosing spondylitis, dermatomyositis, scleroderma, psoriatic arthritis and many other diseases are associated with collagen in one way or another.
Summary
In summary, collagen is a type of protein that can take up to 22 different forms, depending on the chains that compose it, the order of the amino acids, the relationship with the rest of the cellular elements and the place of location. While up to 9 out of 10 collagen fibers are type I, all of them play an essential role in long-term well-being.
In addition, collagen is part of the skin, so it is often associated with anti-aging products and rejuvenating creams. Aging, smoking, exposure to ultraviolet radiation and other events can reduce collagen production and degrade existing collagen, leading to wrinkles and the typical appearance during senescence.
