Chemistry > Biomolecules > 5.0 Amino Acids
Biomolecules
1.0 Carbohydrates
2.0 Monosaccharides
3.0 Disaccharides
4.0 Polysaccharides
5.0 Amino Acids
6.0 Proteins
7.0 Classification of Vitamins
8.0 Nucleic acids
5.1 Classification of Amino Acids
- Depending on the relative position of amino group with respect to carboxylic group, they are classified as $\alpha$, $\beta$, $\gamma $, $\nu $ and so on. Only $\alpha$-amino acids are obtained on hydrolysis of proteins.
- Depending upon the number of amino and carboxyl groups in the molecule, they are classified as:
Acidic: More carboxyl groups as compared to amino groups.
Basic: More amino groups as compared to carboxyl groups.
Neutral: Equal number of amino and carboxyl groups.
- Non Essential Amino Acids: The amino acids which can be synthesized in the body.
- Essential Amino Acids: Those amino acids which cannot be synthesized in the body and must be obtained through diet.
S. No | Name of the amino acids | Characteristic feature of side chain, $R$ | Three letter symbol | One letter code |
1 | Glycine |
| Gly | G |
2 | Alanine |
| Ala | A |
3 | Valine* |
| Val | V |
4 | Leucine* |
| Leu | L |
5 | Isoleucine* |
| Ile | I |
6 | Arginine* |
| Arg | R |
7 | Lysine* |
| Lys | K |
8 | Glutamic Acid |
| Glu | E |
9 | Aspartic Acid |
| Asp | D |
10 | Glutamine |
| Gln | Q |
11 | Asparagine |
| Asn | N |
12 | Threonine* |
| Thr | T |
13 | Serine |
| Ser | S |
14 | Cysteine |
| Cys | C |
15 | Methionine* |
| Met | M |
16 | Phenylalanine* |
| Phe | F |
17 | Tyrosine |
| Tyr | Y |
18 | Tryptophan* |
| Trp | W |
19 | Histidine* |
| His | H |
20 | Proline |
| Pro | P
|
*essential amino acids
Note: Except glycine, all other naturally occurring ?-amino acids are optically active, since the $\alpha$-carbon atom is asymmetric. These exists both in ‘$D$’ and ‘$L$’ forms.
