2.3. Chemistry of Peptide Bonds

•  “Peptides” are small condensation products of amino acids
• They are “small” compared to proteins (di, tri, tetra… oligo-).
• C=N double bond character due to the resonance structure
• Restricted rotations about C=N resists hydrolysis

2.3.1. Reading the AA in a Peptide Chain

• By convention, peptide sequences are written left to right from the N-terminus to the C-terminus.

2.3.2. Naming a Peptide Sequence

1. Naming starts from the N-terminus
2. Sequence is written as: Ala-Glu-Gly-Lys
3. Sometimes the one-letter code is used: AEGK

2.3.3. Peptides: A Variety of Functions

Figure 2.12: Schematic presentation to show a variety of applications of peptides.