- 20 amino acids are commonly found in proteins.
- The 11 amino acids that the human body makes are called non-essential amino acids.
- The 9 amino acids that the human body needs but cannot make are called essential amino acids. These must be eaten.
- Amino acids contain both an amine (-NH2) and a carboxylic acid (-COOH) functional group.
- α-amino acids, or 2-amino acids, are amino acids in which both functional groups are attached to the same carbon atom.
- The general formula for a 2-amino acid (α-amino acid) is:
H2N - R
- COOH Where R is a carbon containing side chain or branch.
This carbon side chain may also contain sulfur, nitrogen or oxygen.
- Amine groups are basic (proton acceptor), carboxylic acid groups are acidic (proton donator).
- Amino acids are both amphiprotic (can accept or donate protons) and amphoteric (can react with acids or bases).
- A zwitterion is the representation of the dipolar amino acid.
- For each amino acid there is a particular pH, the isoelectric point, at which the amino acid exists as the neutral zwitter ion.
⚛ Below this pH the amino acid exists as a positively charged ion (cation).
⚛ Above this pH the amino acid exists as a negatively charged ion (anion).