What are the wavelengths for IR spectroscopy focused on proteins?

The correct choice, which focuses on infrared (IR) spectroscopy in the context of proteins, emphasizes the importance of particular wavelength ranges that facilitate the examination of molecular vibrations associated with bonds in proteins.

IR spectroscopy typically operates in the range of 780 to 3000 nm, which corresponds to the near-infrared and mid-infrared regions. Within these ranges, proteins have characteristic absorption bands associated with their functional groups and secondary structures such as alpha-helices and beta-sheets. Specifically, the amide I band, which is crucial for analyzing protein secondary structure, is found around 1600-1700 cm⁻¹, correlating with wavelengths in the IR spectrum.

In contrast, the other wavelength ranges provided in the incorrect choices do not align with the IR spectrum. The range from 400 to 700 nm corresponds to visible light, and the 300-500 nm and 600-800 nm ranges do not overlap with the infrared spectrum, thereby limiting their applicability to IR spectroscopy for protein analysis. Thus, the identification of infrared wavelength ranges as between 780 to 3000 nm is foundational for effective spectroscopic studies of proteins.