19.1 Structure of Amino Acids Zwitterion: A molecule that has an protonated amino group and a deprotonated carboxyl group

Amino Acids are amphiprotic; they can react either as acids or as bases
- In aqueous acid solution, an amino acid zwitterion is a base that accepts a proton to yields a cation
- In aqueous base solution, an amino acid zwitterion is an acid that loses a proton to yields an anion

All 20 amino acid commonly found in proteins are alpha-amino acids
Alpha-amino acid: The amino acid is a substituent on the alpha-carbon

And 19 of them are primary amines, which means only the side chain on the alpha-carbon is the only difference between the 19 amino acids

The 20th one is "Proline" and is a secondary amine, its nitrogen and carbon atoms are part of a ring.

The 20 common amino acids can be classified as; neutral, acidic or basic - depending on the structure og their side chains.
- An extra amino group would make the amino acid basic.
- An extra carboxyl group would make the amino acid, acidic.

	Created by Mane Sahakian over 9 years ago

Bachelor Bioorganic Chemistry Note on 19 Biomolecules: Amino Acids, Peptides, and Proteins, created by Mane Sahakian on 12/09/2015.