When protein is heated or encounters heavy metal salts such as concentrated nitric acid and mercury nitrate and organic solvent chemicals such as formaldehyde, it will undergo chemical changes and lose its original physiological functions. This process is called protein's "transsexuality".
When saturated ammonium sulfate solution was added to egg white, the observed phenomenon was precipitation, which indicated that saturated ammonium sulfate solution would reduce the solubility of protein. This process is called "salting out" by protein, which is a physical change.
When protein is heated or exposed to concentrated nitric acid, heavy metal salts, formaldehyde and other chemicals, it will undergo chemical changes and lose its original physiological functions. This process is called protein's "transsexuality". Therefore, heavy metal salts and formaldehyde can poison people. If a small amount of heavy metal salt is poisoned, protein can be swallowed to detoxify. Protein smells of burnt feathers after burning. This characteristic can be used to identify protein. The method of distinguishing silk from cotton yarn is as follows: light silk and cotton yarn respectively.