Peptide Characterization
Peptide Characterization Methods
Beyond molecular weight and purity, comprehensive peptide characterization requires multiple analytical techniques.
Analytical Technique Matrix
| Property | Primary Method | Confirmatory Method |
|---|---|---|
| <strong>Molecular Weight</strong> | ESI-MS | MALDI-TOF |
| <strong>Purity</strong> | RP-HPLC (214 nm) | RP-HPLC (254 nm) |
| <strong>Identity</strong> | MS/MS sequencing | NMR (for short peptides) |
| <strong>Aggregation</strong> | SEC-HPLC | DLS, AFM |
| <strong>Secondary Structure</strong> | Circular Dichroism | FTIR |
| <strong>Net Charge</strong> | Capillary electrophoresis | Ion-exchange HPLC |
Circular Dichroism (CD) Spectroscopy
Spectral Signatures
| Structure | Minima | Maxima |
|---|---|---|
| <strong>Alpha-helix</strong> | 208, 222 nm | 192 nm |
| <strong>Beta-sheet</strong> | 218 nm | 195 nm |
| <strong>Random coil</strong> | 195 nm | — |
Aggregation Assessment
- Thioflavin T (ThT) fluorescence: 440 nm excitation, 485 nm emission
- Dynamic Light Scattering (DLS): Hydrodynamic radius distribution
- Transmission Electron Microscopy (TEM): Direct visualization
See [[HPLC Analysis]], [[Mass Spectrometry]], [[Peptide Science Overview]]