Amino acids-what they consist of, classification, role

Amino acidsAmino acids are the fundamental building blocks of proteins and play a key role in biological processes. There are a total of 22 standard amino acids used for protein synthesis in living organisms. are organic compounds that are the main building blocks of proteinsProteins are high-molecular organic substances consisting of alpha-amino acids linked in a chain by a peptide bond. In living organisms, the amino acid composition of proteins is determined by the genetic code. During synthesis, 20 standard amino acids are used in most cases. Many combinations of them determine the great diversity of properties of protein molecules. Proteins play a key role in the immune response and can perform transport, storage, catalytic, structural, and receptor functions. Proteins are an important part of the nutrition of animals and humans. The main sources of proteins are meat, poultry, fish, milk, nuts, legumes, and grains.. They play a key role in biological processes such as protein synthesis, cell signaling, and metabolism. Each amino acid consists of certain chemical elements and functional groups. Let’s analyze their structure in detail.

---

Main components of the amino acid:

1. Central carbon atom (α-carbon):
   • This is the central atom in the structure of an amino acid, to which all other groups are attached.
   • It is a chiral center (with the exception of glycineGlycine is an amino acid that regulates metabolic processes in the central nervous system. It belongs to neurotransmitters (participates in the transmission of nerve impulses). Glycine is a key component of collagen, which gives structure to bones, muscles, connective tissues, and skin. It also participates in the transmission of nerve impulses, increasing the efficiency of information transfer between neurons.), which means that amino acids can exist as two optical isomers (L – and D-forms). In nature, L-amino acids are more common.
2. Amino Group (-NH₂):
   • This is the main group, which contains a nitrogen atom bound to two hydrogen atoms.
   • The amino group gives the amino acid its basic properties.
3. Carboxyl group (-COOH):
   • It is an acidic group consisting of a carbon atom bonded to two oxygen atoms and one hydrogen atom.
   • The carboxyl group gives the amino acid acidic properties.
4. Hydrogen Atom (-H):
   • A simple hydrogen atom bound to an α-carbon.
5. R-group (side chain):
   • It is a unique part of an amino acid that distinguishes one amino acid from another.
   • The R-group can be simple (like glycine, where it is just a hydrogen atom) or complex (like arginine, where it is a long carbon chain with additional functional groups).
   • The properties of the R-group determine the chemical and physical characteristics of the amino acid (for example, hydrophobicity, hydrophilicity, charge).

---

General Amino Acid Formula:

• H is hydrogen.
• nh₂ is an amino group.
• COOH is a carboxyl group.
• R — side chain (variable part).

---

Classification of amino acids:

Amino acids are classified according to the properties of their R-groups:

1. Nonpolar (hydrophobic):
   • Examples: alanine, valine, leucine, isoleucine.
   • These amino acids are poorly soluble in water.
2. Polar uncharged:
   • Examples: serine, threonine, asparagine, glutamine.
   • These amino acids have polar side chains, but do not carry a charge.
3. Charged (acidic and basic):
   • Acidic: aspartic acid, glutamic acid (have a negative charge).
   • Basic: lysineLysine is an essential amino acid that is one of the main components of protein molecules with pronounced basic properties. In DNA, it is encoded by the sequences AAA and AAG. It is the foundation that makes up protein — the building material for the body's cells and tissues.  The body cannot produce lysine on its own; the amino acid enters it with food or through taking special supplements., arginine, histidineHISTIDINE is a heterocyclic amino acid. It is part of many proteins. It is the starting material for the biosynthesis of histamine and biologically active muscle peptides - carnosine and anserine. (have a positive charge).
4. Aromatic products:
   • Examples: phenylalanine, tyrosine, tryptophan.
   • These amino acids contain aromatic rings in their side chains.

---

The role of amino acids in the body:

1. Protein Synthesis: Amino acids are linked in chains through peptideA peptide is a molecule consisting of a chain of amino acids linked together by peptide bonds. Peptides are shorter chains than proteins and usually contain from 2 to 50 amino acids. When the number of amino acids in a chain exceeds 50, such molecules are called proteins. Peptides can perform various functions in the body, including: Hormones, Neuropeptides, Antibiotics, Antioxidants bonds to form proteins.
2. Metabolism: Some amino acids are involved in the synthesis of other important molecules, such as neurotransmitters (eg, glutamate, GABA).
3. Energy metabolism: Amino acids can be used as a source of energy during digestion.
4. Signaling: Some amino acids (such as glycine, glutamate) function as neurotransmitters.

---

Conclusion

Amino acids are fundamental molecules consisting of an amino group, a carboxyl group, hydrogen, and a unique side chain (R-group). Their diversity and properties determine their role in protein construction and other biological processes. Understanding the structure of amino acids helps to understand their functions and significance for life.