Denaturation is the action of proteins affected by physical or chemical factors that change the internal structure and properties of their molecules. It is generally believed that the secondary and tertiary structures of proteins are altered or destroyed as a result of denaturation. Chemical methods that can denature proteins include strengthening acids, strong bases, heavy metal salts, urea, ethanol, acetone, etc. Physical methods that can denature proteins include heating, ultraviolet irradiation, and violent oscillation. Heavy metal salts denature proteins because heavy metal cations can form insoluble salts with free carboxyl groups in proteins, and there is chemical bond breaking and generation in the denaturation process, so it is a chemical change. Strong acids and bases denature proteins because they can break hydrogen bonds in proteins. They can also form salts with free amino or carboxyl groups, and there is also breaking and generation of chemical bonds during the change, so it can be regarded as a chemical change. Urea, ethanol, acetone, etc., which can provide their own hydroxyl or oxygen on the carbonyl group to form a hydrogen bond, thus breaking the original hydrogen bond in the protein and denaturing it. However, the hydrogen bond is not a chemical bond, so there is no breaking or creation of a chemical bond during the change, so it is a physical change. Heating, ultraviolet irradiation, violent oscillation and other physical methods to denature proteins, mainly by destroying the plant protein molecules in the hydrogen bond, in the process of change, there is no chemical bond breaking and generation, there is no new material dust into, so it is a physical change. Otherwise, the egg is not protein after cooking. From the above analysis, we can see that the denaturation of protein has both physical and chemical changes. However, the denaturation of proteins is very complex, to determine whether the denaturation is a physical change or a chemical change, depending on the specific circumstances. If there is a chemical bond breakage and generation is a chemical change; if there is no chemical bond breakage and generation is a physical change. The tight structure of natural proteins in some physical or chemical factors, its specific spatial structure is destroyed, resulting in changes in physical and chemical properties and loss of biological activity, such as the loss of catalytic activity of enzymes, hormones, the loss of activity is called the denaturation of proteins (denaturation). Denaturation of proteins only the destruction of spatial conformation, it is generally believed that the essence of protein denaturation is the destruction of secondary bonds, disulfide bonds, and does not involve changes in the primary structure. The most obvious difference between denatured proteins and natural proteins is that the solubility decreases, while the viscosity of proteins increases, the crystallinity is destroyed, the biological activity is lost, and it is easy to be broken down by proteases. The causes of protein denaturation can be divided into two categories: physical and chemical factors. Physical factors can be heating, pressurization, dehydration, stirring, oscillation, ultraviolet irradiation, the role of ultrasound, etc.; chemical factors are strong acid, strong alkali, urea, heavy metal salts, sodium dodecyl sulfonate (SDS) and so on. In clinical medicine, denaturing factors are often applied to disinfection and sterilization. Conversely, care to prevent denaturation of proteins can lead to effective preservation of protein preparations. Denaturation is not an irreversible change, when the degree of denaturation is mild, such as the removal of denaturing factors, some proteins can still be restored or partially restored to its original conformation and function, the reversible change of denaturation is called reversibility. For example, the four pairs of disulfide bonds and their hydrogen bonds in the aforementioned ribonuclease. In the β slot box ethanol and 8M urea role, denaturation, loss of biological activity, denaturation, such as after dialysis to remove urea, β slot box ethanol, and managed to oxidize the hydrophobic group into disulfide bonds, enzyme proteins can be restored to its original conformation, the biological activity of the enzyme is also almost completely restored, which is known as denaturing ribonuclease rejuvenation. Many proteins are severely damaged when denaturing, and cannot be restored, known as irreversible denaturation We need to know the conditions of protein denaturation, and reasonable treatment of some foods. In order to better condition the body and get better health.