All You Need to Know About Amino Acids

Essential amino acids, as part of proteins, have many different functions in the human body. Find out some of them here!
All You Need to Know About Amino Acids
María Vijande

Written and verified by la farmacéutica María Vijande in 12 August, 2021.

Last update: 12 August, 2021

Amino acids are the simple molecules that make up proteins. In other words, they’re the “building blocks” that make up proteins. They’re responsible for allowing muscle contraction or maintaining the acid-base balance of the body, for example. In addition, each of them has an independent function.

The 20 amino acids that make up proteins are valine, leucine, isoleucine, methionine, phenylalanine, asparagine, glutamic, glutamine, histidine, lysine, arginine, aspartic, glycine, alanine, serine, threonine, tyrosine, tryptophan, cysteine, and proline.

A little history about amino acids

The first amino acid discovered was in the 19th century, thanks to the chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet who isolated a compound from asparagus. As a result of the discovery, they called this amino acid asparagine. Later, cystine was isolated in 1810, although its monomer, cysteine, remained unknown until 1884. Glycine and leucine were discovered in 1820.

The last of the 20 amino acids to be discovered was threonine, in 1935 by William Cumming Rose. This scientist also determined the essential amino acids that we’ll see later and established the minimum daily requirements of all amino acids for optimal human growth.

Types and classification of amino acids

These structures are made up of carbon, oxygen, hydrogen and nitrogen atoms. They’re small organic molecules with an amino group (-NH2) and a carboxyl or acid group (-COOH).

These 20 different amino acids combine with each other to form the different proteins in the body. However, experts have discovered about 200 others that aren’t part of proteins.

Depending on their structure, they can be classified into L and D shapes. The L forms are the natural ones for organisms and, therefore, the most important. In this sense, the 20 proteinogenic amino acids can be divided as follows:

  • Essential: These are the amino acids that the body can’t synthesize and they are obtained through food. They are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
  • Non-essential: Unlike the previous ones, the body is capable of synthesizing them. Among them, we find alanine, asparagine, aspartic acid and glutamic acid.
  • Conditionals: These are necessary to alleviate certain diseases or stress: arginine, glutamine, tyrosine, glycine, proline, and serine.

The terms essential or non-essential doesn’t refer to their importance to the body, since they’re all necessary. The amount necessary for the proper functioning of the body varies depending on the person and their biological needs.

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On the other hand, although there are many ways to classify amino acids, we can also group them according to the number of acidic or basic groups that the molecule contains, or according to its structure.

According to the first classification, we differentiate between acidic, basic and neutral amino acids. According to their structure, we can group them into:

  • Aliphatic
  • Aromatics
  • Sulfur

Functions of essential amino acids

Essential amino acids, as part of proteins, have functions related to the purely structural or plastic character of the protein. Ultimately, its functions include wound repair and the growth and development of the body.

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We’re now going to mention some of the functions of essential amino acids more specifically.

  • Leucine: Used for muscle and bone regeneration. It also controls blood glucose, that is, blood glucose levels, and is related to hormonal processes.
  • Isoleucine: This is also related to the repair of muscles, bones and dermal tissue. In turn, it participates in the formation of hemoglobin, a protein necessary for the transport of oxygen .
  • Methionine: Has antioxidant action, which is why it prevents some risk factors for cardiovascular diseases. It’s also used to treat mental illness.
  • Lysine: This is necessary for the formation of collagen, a fundamental element of the joints. In addition, it participates in the metabolism of calcium and in the formation of antibodies, thus strengthening the immune system.
  • Valine: This amino acid contributes to muscle repair and maintenance. It’s also used in the liver metabolism of some nutrients.
  • Phenylalanine: This participates in the formation of neurotransmitters that stimulate the nerve synapse. It’s related to moods, concentration and learning by its stimulation of the nervous system. The possibility of using it for the treatment of mental illnesses such as Parkinson’s and Alzheimer’s is currently being studied.
  • Tryptophan: This acts on a nervous level as a body relaxant and facilitates falling asleep. In addition, it controls the sensation of appetite. It also has functions opposite to those of phenylalanine. Tryptophan is used in the treatment of hyperactivity.
  • Threonine. Finally, this amino acid has a great effect on the metabolism of fats and also helps in the synthesis of collagen, which, as we have seen, is a fundamental component of the joints.
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