Peptide Circular Dichroism Spectroscopy

Peptide Circular Dichroism (CD) is a powerful spectroscopic technique primarily used for studying the secondary structure of peptides and proteins. It is based on a simple principle: when optically active substances such as peptides absorb circularly polarized light, they produce specific spectral signals. These signals can reveal structural features of proteins and peptides, such as α-helix, β-sheet and random coil structures.

 

In the analysis of peptide CD spectra, scientists often focus on the ultraviolet region, especially wavelengths between 190 and 250 nanometers. Amino acid residues in the peptide chain, like tryptophan, tyrosine, and phenylalanine, strongly absorb light in this region. By analyzing the differential light absorption at these wavelengths, the secondary structure of the peptide can be inferred. For example, the α-helix structure produces specific absorption peaks at 222 and 208 nanometers, while the β-sheet shows characteristic absorption at 215 nanometers.

 

In addition, peptide CD can also be used to monitor structural changes of peptides under different environmental conditions. For instance, by changing the pH, temperature, or ionic strength of the solution, one can study how these conditions affect the structural stability and dynamics of peptides. This is crucial for understanding how peptides fold and perform their functions in biological organisms, as well as how their structures change under disease conditions.

 

In the field of drug development, peptide CD is particularly important. It can help researchers assess how drug candidate molecules influence the structure of specific proteins or peptides. This is especially crucial in designing drugs that can effectively target specific proteins, particularly in diseases involving protein structure abnormalities such as Alzheimer's disease or Parkinson's disease.