What technique uses UV light to analyze secondary structures in proteins?

Circular dichroism (CD) is a powerful spectroscopic technique that utilizes UV light to analyze the secondary structures of proteins. This method is based on the differential absorption of left-handed and right-handed circularly polarized light by chiral molecules, such as proteins. When proteins are subjected to UV light, their secondary structures—such as alpha helices and beta sheets—exhibit unique CD spectra. These spectra provide information about the conformational state of the protein, allowing for the assessment of its folding and stability in solution.

The utility of circular dichroism lies in its ability to rapidly and non-destructively assess protein structure, making it particularly advantageous in studies of protein folding, dynamics, and conformational changes. This technique is especially useful for monitoring changes in protein structure under various conditions, such as changes in pH, temperature, or ligand binding.

In contrast, other methods like X-ray crystallography and nuclear magnetic resonance (NMR) do not rely on UV light or are typically used for different structural analyses. X-ray crystallography requires crystallization of the protein, while NMR involves understanding the magnetic properties of nuclei within the protein. Infrared spectroscopy, while useful for studying functional groups and chemical bonds, does not specialize in revealing protein secondary