Inorganic salt denaturants stabilize ribonuclease against denaturation by urea.

The isothermal denaturation of ribonuclease A by mixed denaturant systems was investigated at 25 degrees C. It was observed that low concentrations of lithium chloride stabilize the protein against denaturation by urea, even though the salt itself is a denaturant. This study also provides, for the first time, the most convincing evidence that the lithium chloride denatured ribonuclease A contains some of the native secondary and tertiary structure.