What are Proteins and Amino Acids?

From our hair and nails to muscles, through hormones, enzymes and antibodies, everything in our body is basically composed of proteins.

Protein structure
Protein structure
 


What is a protein?

Protein is, after water, the most important and most abundant component of living things. Virtually everything in our body is composed primarily of proteins, including our cells.

To facilitate understanding, we will use some analogies throughout this text. Let's start our explanation with a very simple: proteins are for living beings as the bricks are for a house.

Therefore, imagine our organism as a large cluster of small organic stones. Our skin, nails, hair, bones, muscles, etc. are all composed of proteins. It is estimated that there are around 2 million proteins in the human body.

The analogy with the bricks is only meant to begin with. Let's dig deeper into the subject. Proteins are composed much more complex. If in a home there is usually only one type of brick, our body consists of about 50,000 to 100,000 different types of proteins. While the bricks have only the function of giving structure to the house, our proteins go far beyond. Each of the 100,000 proteins plays a role in the body. Even those that are just structural are very different from each other, just notice the differences that exist between hair, skin, muscles, nails, organs, etc.

The role of proteins is not only to give structure to our tissues and organs. Several substances metabolically active in our body are formed by proteins, such as: hormones, antibodies, enzymes, coagulation factors, hemoglobin, etc. In general, 50% of the weight of each of our cells is composed of proteins.

Therefore, protein is not just a brick, it is brick, electricity, water, gas, furniture and everything else that makes a house work. It is as if each of these elements of the house were a different kind of protein.

Some examples of different proteins and their functions:
  • Amylase: an enzyme produced in the pancreas that participates in the process of digestion of carbohydrates.
  • Insulin: a hormone necessary for the entry of glucose into cells.
  • Prolactin: a hormone that stimulates milk production by the mammary glands.
  • Collagen: protein of structural function, responsible for keeping the tissues together, mainly skin, cartilage and bones.
  • Immunoglobulins: are the antibodies responsible for defenses against invading germs.
  • Actin and Myosin: contractile proteins of the muscles, responsible for the contraction capacity of the muscles.
  • Fibrinogen: protein that participates in the process of blood clotting.
  • Ferritin: liver protein used to store iron.

What is protein made of?

Proteins are made from the junction of amino acid molecules, that is, they are polymers of amino acids. Human proteins are formed by randomly combining 20 different types of amino acids, namely:

Imagine each of the 20 amino acids above as a LEGO piece. If you have 20 different pieces, but each one of them in a gigantic number, the amount of shapes you can create is virtually endless. As mentioned above, in the human body, the 20 molecules of amino acids create something around 100,000 different proteins with different functions, size, shape, composition and number of amino acids.

A protein is made up of at least 50 amino acid molecules. This is your minimum size. Already the largest proteins in the human body have more than 30,000 amino acids. Structures formed by less than 50 amino acids are called peptides. Like proteins, peptides also play important roles in the body.

Insulin, a hormone produced by the pancreas, which acts by allowing glucose to enter cells, is a small protein composed of only 51 amino acids (it is the junction of two peptides, one of 21 amino acids and one of 30 amino acids). Hemoglobin, a structure found in red blood cells, responsible for transporting oxygen, is a more complex protein composed of 574 amino acids. Some muscle proteins are huge, being made up of more than 30,000 amino acids.

In addition to the amount and types of amino acids present, the form the protein assumes also influences its function. The protein may have a linear, helical, foldable or somewhat spherical structure. Just as a sheet of paper, depending on how it is folded, can give rise to a small boat, a hat or an airplane, two proteins composed of the same amino acids, can take different forms, and perform different functions in the body.

Essential amino acids

Of the 20 amino acids that the body uses as a basis for the production of its proteins, 11 are produced by our own organism and 9 are obtained exclusively through food. These 9 amino acids that the body can not produce (phenylalanine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, histidine and valine) are called essential amino acids. If only one of them is missing, thousands of essential life proteins will no longer be produced, causing serious damage to health.

Essential amino acids can be obtained through variety of foods such as meats, cereals, vegetables, grains, soy, eggs and milk. A balanced diet is more than enough to provide the amount of amino acids we need. Even people who do not eat meat can eat all the essential amino acids.

Protein supplements

The use of protein and amino acid supplements has become very common, especially among people who want to gain muscle. Muscles are basically composed of proteins, many of them produced through essential amino acids. If you intend to build muscles, you need to have proteins in the body for the job, after all, you do not build a house without bricks.

However, do not just eat protein to get stronger. One of the rules of our body is just to use what you need, storing the rest in case there is a shortage of food in the future. Our organism has been shaped by centuries of evolution, always waiting for difficult times, with a lack of food. Supermarkets, refrigerator, and overeating are a creation of modern man. Our body still thinks like our ancestors, who did not have so easy access to food. Everything that is consumed in excess turns fat, which is a source of energy that can be stored in large quantities.

The production of muscles is encouraged by physical exercise. If a certain muscle is constantly being required, the body automatically increases the supply of protein, making it stronger. In this case, it is necessary to ensure a good intake of proteins so that they can serve as a substrate for the production of larger and stronger muscle fibers. If the individual, however, is sedentary or only makes slight efforts, the body does not feel the need to create more muscles, since the present musculature is sufficient to withstand the daily load of efforts. In this case, if the subject consumes more protein than necessary, they will not be harnessed. As each gram of protein has about 4 calories, the body will turn the excess calories ingested into fat, storing them in the fatty tissues.
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