Factors affecting the line widths and signal‐to‐noise ratios of the ¹³C CP/MAS spectra of proteins

Typically the 13 C CP/MAS spectra of proteins have low signal‐to‐noise ratios and broad lines, which considerably degrade the value of such spectra. The origins of these effects were examined using a model protein, lysozyme. The effects of hydration, relaxation time and crystallinity were systematically investigated. It is concluded that low signal‐to‐noise ratios are the result of the typically low density of protein preparations and not an intrinsic magnetic resonance phenomenon, and that line broadening is principally the result of poor molecular packing in noncrystalline protein preparations.