Amino Acid Structure And Formula
- A protein molecule consists of one or more long unbranched polymer chains composed of numerous small subunits or monomers is called amino acids.
- There are 20 amino acids from which 18 have the same structure.
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LINKAGE OF AMINO ACIDS
- In protein, the amino acids link up in such a way that the amino group of one amino acid is joined to the carboxyl group of the adjacent one with the loss of water molecule for each linkage as a byproduct.
- The amino group contributes hydrogen and the carboxyl group contributes hydroxyl group (-OH) to water.
- The covalent bond joining the two amino acid unit by –NH-CO linkage is called Peptide Bond. It is formed by the process of condensation ( Dehydration ) i.e loss of water.
- A chain of two amino acids is called Dipeptide. A chain of three amino acid is called Tripeptide, of a few ( less than 30 ), Amino acid and Oligopeptide, and of many ( more than 30 ), Amino acid are Polypeptide.
FUNCTION Of Amino Acid
- VALINE: Helps in the growth of muscles.
- ISOLEUCINE: Plays a vital role in the synthesis of hemoglobin and its major component of RBC.
- METHIONINE: Helps in maintaining good and healthy skin.
- LEUCINE: It promotes the synthesis of growth hormones.
- LYSINE: They are involved in the synthesis of enzymes and other hormones.
- HISTIDINE: Helps in the production and synthesis of both RBC and WBC.
- Non- essential
- ALANINE: Helps in the removal of toxins from our body.
- CYSTEINE: Provides resistance to our body and inhibits the growth hairs, nails and etc.
- GLYCINE: It acts as a neurotransmitter and plays a vital role in healing wounds.
- ARGININE: It promotes the biosynthesis of proteins.
- TYROSINE: It plays a vital in the production of T3 and T4 thyroid hormones.
CLASSIFICATION Of Amino Acid
Based on nature
ACIDIC AMINO ACIDS: These contain one amino group and two carboxyl groups per molecule. These are called monoamine-dicarboxylic amino acids. Example – Aspartic acid, Glutamic acid.
BASIC AMINO ACIDS: These contain two amino groups and one carboxyl group per molecule. These are called as diamino- monocarboxylic amino acids. Example – Lysine, Arginine.
NEUTRAL AMINO ACIDS: These have one amino group and one carboxylic group per molecule. These are called monoamine- monocarboxylic amino acids. Example – Glycine, Valine.
Based on the special structure
- SULPHUR CONTAINING AMINO ACIDS: These amino acids contain sulfur.
Example: Methionine, Cysteine.
- ALCOHOLIC AMINO ACIDS: These amino acids contain an alcoholic group.
Example – Serine, Threonine, Tyrosine.
- AROMATIC AMINO ACIDS: These amino acids contain phenyl rings.
Example – Phenylalanine, Tryptophan
- HETEROCYCLIC AMINO ACIDS: These amino acids contain a heterocyclic ring.
Example – Proline
Based on nutritional requirement
ESSENTIAL AMINO ACIDS: There are a few amino acids that cannot be synthesized by the body.
Examples: Phenylalanine, Valine, Leucine, Lysine, Methionine, Histidine.
NON ESSENTIAL AMINO ACIDS: There are few amino acids which are easily biosynthesized by our body.
Examples: Alanine, Cysteine, Cystine, Glutamine, Glycine, Glutamate, Arginine, Tyrosine, Serine, Asparagine, Aspartic acid, Proline.
Based on polarity
POLAR AMINO ACIDS
Serine, Threonine, Glutamine, Asparagine, Cysteine.
a)Positively charged: Arginine, Lysine, Histidine.
b)Negatively charged: Glutamate, Aspartate.
NON-POLAR AMINO ACIDS
Proline, Valine, Leucine, Isoleucine, Methionine.
Tyrosine, Phenylalanine, Tryptophan.