The building blocks of proteins are amino acids. Amino acid is an organic compound containing an amino group (-NH2) and a carboxyl group (-COOH). It was discovered by Emil Fischer and Franz Hofmeister in 1902. The number of protein amino acids in the human body is 20. Leucine, isoleucine, lysine, methionine, serine, valine. , proline, alanine, threonine, tyrosine, histidine, cysteine, asparagine, glycine, arginine, tryptophan, glutamic acid, glutamine, aspartic acid and phenylalanine.
Characteristics of amino acids
1. It is soluble in water, but insoluble in alcohol.
2. It is a tasteless, sweet or bitter substance.
3. It forms salts with mild acids or bases.
4. They have high melting point.
5. It is bisexual.
6. Its elements are called Zuitter Ions.
7. It is linked by peptide bonds to form proteins.
8. Human body contains alpha amino acids.
9. It contains at least one amino group and one carboxyl group.
10. Amino acids are obtained by hydrolysis of pure protein.
Chemical structure of amino acids
The common symbol for amino acids is R-CH. NH2.COOH. Amino acids contain amino group ((-NH2), carboxyl group (-COOH) and side chain group (R).
Classification of amino acids
There are 28 amino acids in plants and animals. They are divided into three categories.
1. Aliphatic Amino Acids: If the side chain group (R) of an amino acid is aliphatic, it is called an aliphatic amino acid. Aliphatic amino acids are divided into five groups.
(i) Monoamino monocarboxylic acid: An amino acid having one amino group and one carboxyl group is called monoamino monocarboxylic acid. For example, Alanine, Leucine, Isoleucine, Glycine, Valine etc
(ii) Monoamino dicarboxylic acid: An amino acid having one amino group and two carboxyl groups is called monoamino dicarboxylic acid. For example – glutamic acid, aspartic acid etc.
(iii) Diamino monocarboxylic acid: The amino acid containing two amino groups and one carboxyl group is called diamino monocarboxylic acid. For example, lysine, arginine etc.
(iv) Monoamino monohydroxylic acid: An amino acid having one amino group and one hydroxyl group is called monoamino monohydroxylic acid. For example, serine, threonine etc.
(v) Sulphur-containing amino acids: Amino acids that contain amino groups, hydroxyl groups and sulfur are called sulfur-containing amino acids. For example, methionine, cystine etc.
2. Aromatic Amino Acids: If the side chain group (R) of an amino acid is an aromatic compound, it is called an aromatic amino acid. For example, phenyl alanine, tyrosine etc.
3. Heterocyclic Amino Acids: When opposite religion of aliphatic and aromatic is observed in amino acid, it is called heterocyclic amino acid. Eg- tryptophan, histidine, proline etc.
Amino acids are divided into two categories based on protein structure.
1. Protein amino acid: All the amino acids that form proteins are called protein amino acids. Protein is 20 amino acids. Glycine, lysine, valine, alanine, tyrosine, leucine, isoleucine, aspartic acid, glutamic acid, asparagine, glutamine, arginine, cystine, serine, methionine, threonine, phenylalanine, histidine, tryptophan and proline.
2. Non-protein amino acid: All the amino acids that do not participate in the formation of proteins are called non-protein amino acids. More than 700 non-protein amino acids. Of these, 300 are found in plants. Such as Ornithine, Homoserine, Homocysteine, Citrulline etc.
Amino acids are of two types based on requirement.
1. Essential amino acid: All amino acids that cannot be synthesized in the body are called essential amino acids. For example, leucine, isoleucine, lysine, tryptophan, phenylalanine, threonine, valine, methionine etc. 10 essential amino acids for children.
2. Non-essential amino acid: All the amino acids that are synthesized in the body are called non-essential amino acids. 12 non-essential amino acids.
Polar & non-polar amino acids
1. Non-polar amino acids. 10 (alanine, valine, glycine, proline, leucine, isoleucine, methionine,
Tryptrophin and phenylalanine.
2. Polar un-charged amino acids. 5 (serine, threonine).
3. Polar positively charged amino acids. 3 (lysine, histidine).
4. Polar negatively charged amino acids. 2 (glutamic)
Importance of amino acid
1. Protein synthesis: Amino acids are joined by peptide bonds to form proteins.
2. Plasma protein production: It produces blood plasma proteins.
3. Synthesis of chemical substances: enzymes, vitamins, antibodies, urea etc
Amino acids help in synthesis.
4. Hormone production: Hormones are produced by synthesizing amino acids in the endocrine glands
by doing The plant hormone participates in the formation of indole acetic acid.
5. Melanin production: It produces melanin in the body.
6. Produces milk protein: It produces milk protein carcinogens.
7. Structure of the body: Amino acids form the body structure of the organism.
8. Increase immunity: Amino acid increases the immunity of the body.
9. pH control: Amino acids help in pH control in the body.
10. Enzyme Synthesis: All types of enzymes are made from amino acids.
11. Urea synthesis: Amino acids help in urea synthesis.
12. Formation of Glucose: The removal of the amino group from the carbon chain of various amino acids forms glucose.