What technique primarily utilizes IR wavelengths for protein analysis?

Infrared spectroscopy is the technique that primarily utilizes infrared (IR) wavelengths for protein analysis. This method is based on the principle that molecules absorb specific frequencies of infrared light, which corresponds to the vibrational motions of their bonds. When proteins are subjected to IR radiation, the absorption of these wavelengths results in a unique spectral fingerprint that can be used to identify structural features, functional groups, and conformational changes within the protein.

Infrared spectroscopy is particularly useful for studying the secondary structures of proteins, such as alpha-helices and beta-sheets, because the amide bonds in the polypeptide chains show specific absorption patterns in the IR region. This ability to provide information about molecular structure contributes significantly to understanding protein function and interactions.

In contrast, techniques like X-ray crystallography rely on the diffraction of X-rays through crystalline protein samples to resolve atomic structures. Mass spectrometry measures the mass-to-charge ratio of ions to analyze proteins and their fragments, often requiring their ionization. Electrophoresis separates proteins based on size or charge through a gel matrix. Each of these techniques has its unique advantages and applications but does not involve the use of infrared wavelengths for analysis as infrared spectroscopy does.