The fascinating world of proteins: their role and functioning

quest ce que les proteines

In daily life, we often hear about the importance of proteins for our health and well-being. But what exactly is protein? This article looks at the crucial role of these essential molecules in our body.

Structure and composition of proteins

Proteins are macromolecules that actively participate in the majority of biological processes in our body. They consist of a linear chain ofamino acids, which themselves are composed mainly of carbon, hydrogen, oxygen and nitrogen. Proteins can be extremely complex, with over 20 different amino acids forming unique combinations for each specific protein.

Link between amino acids and proteins

There are 22 amino acids commonly found in proteins, nineteen of which have a similar shape with a distinct “side chain” determining them. Eight of these amino acids are called “essential” because our body cannot synthesize them on its own and must therefore obtain them through a healthy and balanced diet. Peptide bonds between amino acids form the primary structure of the protein. More complex secondary and tertiary structures are then created by folding the amino acid chain according to specific interactions.

Role and function of proteins in the body

Protein serves a multitude of vital functions for our body. They contribute to the construction and repair of tissues, the proper functioning of the immune system, the transport and storage of crucial molecules and also serve as catalysts for enzymatic reactions. Here are some concrete examples of the different roles that proteins play:

  • Biochemical catalyst: Enzymes are proteins that speed up chemical reactions in the body.
  • Structure and support: Collagen, keratin and actin are part of the structure of cells, tissues or organs to give them strength and resistance.
  • Movement : Myosins allow muscles to contract and its fibers ensure the mobility of each individual.
  • Transportation : Hemoglobin transports oxygen while transferrin helps transport iron in the blood.
  • Immune response: Antibodies are proteins that bind to antigens, thereby enabling the destruction of these intruders.
  • Cellular communication: Protein receptors located on the cell membrane allow cells to receive and respond to chemical signals.

Protein intake: natural sources and diet

A balanced diet is essential for sufficient protein intake. There are numerous natural sources of this molecule, whether they are foods of animal or plant origin. Here are some examples:

  • Animal origin: Meats (beef, chicken, pork), fish, eggs, dairy products (milk, cheese, yogurt).
  • Plant origin: Legumes (lentils, chickpeas, beans), grains (quinoa, rice, wheat), seeds (chia, flax), nuts and tofu.

Among these foods, some offer a complete amino acid profile such as animal products and quinoa. For a vegetarian diet, it is therefore interesting to consume different types of plant proteins in order to obtain a complete supply of essential amino acids.

Protein synthesis and breakdown in the body

Protein synthesis begins with the transcription of DNA into messenger RNA followed by the translation of mRNA into a polypeptide chain. This process takes place through various biomolecules like transfer RNA and ribosomes, which assemble amino acids to create a specific protein.

Proteins have a variable lifespan in the body: some are rapidly degraded while others can persist for weeks or even months. Protein degradation occurs through the ubiquitin-proteasome system, where ubiquitin-tagged proteins are directed to structures called proteasomes to be degraded into small peptides and free amino acids. These are then reintegrated into the metabolic pathway in order to participate in the synthesis of other proteins or provide energy for the body.