Amino Acids & Peptides
| AMINO ACIDS (subunits of peptides) = | |
SOME AMINO ACID EXAMPLES
| R Group | Name of Amino Acid | Interesting property of Amino Acid |
| -H | Glycine | Simplest amino acid |
| -CH2-SH | Cysteine | 2 cysteines can form cross-links between peptide chains |
| -CH2-COOH
-CH2-CH2-COOH |
Aspartic acid
Glutamic acid |
Have a negative charge at intracellular pH |
| -CH2-CH2-CH2-CH2-NH2 | Lysine | Has a positive charge at intracellular pH |
| -CH-CH3 | CH3 |
Valine | Not polar; avoids H2O |
For the names and formulas of all 20 common amino acids, see text.
PEPTIDE BOND = bond between a carboxyl and an amino group
PEPTIDES = chains of amino acids connected by peptide bonds
Note that:
1) The chain has a regular repeating
structure (backbone without R-groups)
2) All the R groups stick out