Amino Acids
Proteins are the most common compound in living organisms and consist of carbon, hydrogen, oxygen, nitrogen and in rare cases with other atoms. A protein is a molecule of amino acids. The composition of animal protein involves 20 amino acids that have a common structure: a carbon atom is located in the center, an amino group is attached to it (NH 2), a hydrogen atom (H), a carboxyl group (COOH) and the fourth bond is occupied by a group defining an amino acid, denoted radical. So, for glycine it will be a hydrogen atom, for alanine it will be a group CH3.| Name | Radical |
|---|---|
| Alanine | CH3 |
| Arginine | (CH2)3-NH-C(=NH)(-NH2) |
| Asparagine | CH2-C(=O)(-NH2) |
| Aspartic acid | CH2-COOH |
| Valin | CH(-CH3)(-CH3) |
| Histidine | CH2-C(=1)(-NH-CH-N-CH=1) |
| Glycine | H |
| Glutamine | CH2-CH2-C(=O)(-NH2) |
| Glutamic acid | CH2-CH2-COOH |
| Isoleucine | CH(-CH3)(-CH2-CH3) |
| Leucine | CH2-CH(-CH3)(-CH3) |
| Lysine | (CH2)4-NH2 |
| Methionine | CH2-CH2-S-CH3 |
| Proline | CH(-1)(-NH-CH2-CH2-CH2-1) |
| Serine | CH2OH |
| Tyrosine | CH2-C6H6-OH |
| Threonine | CH(-CH3)(-OH)(-H) |
| Tryptophan | CH2-C(=CH-NH-1)(-(1,21)C6H6) |
| Phenylalanine | -CH2-C6H6 |
| Cysteine | CH2-SH |
| Table 1.Proteinogenic amino acids | |
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Synthesis
Proteins are synthesized as a result of the dehydration reaction: the OH ion of the carboxyl group of an amino acid and the H ion of the amino group of another acid form a water molecule, the released carbon and nitrogen "bonds" form a bond that is called peptide, the resulting molecule is classified as a peptide.
(Amino Acid)-COOH + HN-(Amino Acid) → Dipeptide + Water
By a similar reaction, subsequent amino acids are added, as a result forming a long peptide chain, in known molecules there are from three to thousands of amino acids, the molecules are designated polypeptides. Protein is a polypeptide chain consisting of 100 or more amino acids. The number of proteins is infinite, since each is formed by a combination of 20 amino acids in a different order.
Functions
Proteins are one of the main types of molecules that are part of almost all living beings, both at the cellular level and forming skin, nails, hair, and so on. They are enzymes - they control most of the chemical processes in the cell, including the flow of chemical elements in the cell. Antibodies are also proteins - they protect the body from infections and diseases. Hormones, such as insulin, are also proteins. Proteins also act as an energy buffer: egg white and casein. The representative of the transport function is hemoglobin, which carries oxygen in the body.
