Polar amino acids
Polar amino acids
There are twenty amino acids, five of which are polar but uncharged. Two of which contain a hydroxyl group (-OH) attached to aliphatic side chain that is serine and threonine. As for the asparagine and glutamine they contain a terminal carboxamide in place of carboxylic acid. The fifth polar amino acid is cysteine that is structurally similar to serine but contain a sulfhydryl, or thiol (-SH), instead of the hydroxyl (-OH) group. All amino acids in solutions of a neutral pH form dipolar ions called zwitterions, the amine group being positive and the carboxyl group negative [1].
| Serine | Ser | S |
| Cysteine | Cys | C |
| Threonine | Thr | T |
| Glutamine | Gln | Q |
| Asparagine | Asn | N |
References
- ↑ Berg J., Tymoczko J and Stryer L, (2007) Biochemisty, 6th edition, New York: WH freeman.