Protein is the material basis of life. Without protein, there would be no life. Therefore, it is a substance closely related to life and various forms of life activities. Protein participates in every cell and all important parts of the body. Protein accounts for 16.3% of human body weight, that is, an adult weighing 60kg has about 9.8kg of protein in his body. There are many kinds of protein in human body, with different properties and functions, but they are all composed of more than 20 kinds of amino acids in different proportions, which are constantly metabolized and updated in the body. The ingested protein is digested and decomposed into amino acids in the body, which is mainly used to recombine into human protein according to a certain proportion after absorption. At the same time, the new protein is constantly metabolized and always in a dynamic balance. Therefore, the quality and quantity of food protein and the proportion of various amino acids are all related to the amount of protein synthesized by the human body, especially the growth and development of teenagers, the prenatal and postnatal care of pregnant women and the health and longevity of the elderly, which are closely related to the amount of protein in the diet. [Edit this paragraph] protein protein is composed of biological macromolecules with amino acids as the basic unit. [Edit this paragraph] protein protein is composed of C (carbon), H (hydrogen), O (oxygen) and N (nitrogen). Generally, protein may also contain phosphorus, sulfur, iron, zinc, copper, boron, manganese and iodine. [Edit this paragraph] The nature of protein ① has both sexes.
Protein is a polymer compound composed of α-amino acids through peptide bonds, and protein has amino groups and carboxyl groups, so like amino acids, protein is also an amphoteric substance.
② Hydrolysis reaction can occur.
Protein undergoes hydrolysis reaction under the action of acid, alkali or enzyme, and finally a variety of α -amino acids are obtained through polypeptide [1].
When protein is hydrolyzed, it is necessary to accurately find the "breaking point" of the bond in the structure and hydrolyze the peptide bond.
Such as: protein
nH2N-CH2-COOH
The products of protein hydrolysis can be determined by finding the "breaking point".
Such as protein hydrolysis.
Three α -amino acids, namely H2n-CH2-COOH, can be obtained.
③ Soluble water has colloidal properties.
Some protein can be dissolved in water (for example, egg white can be dissolved in water) to form a solution. Have colloidal properties.
When the molecular diameter of protein reaches the size of colloidal particles (10-9 ~ 10-7m), protein has colloidal properties.
④ Adding electrolyte will produce salting-out.
A small amount of salt (such as ammonium sulfate, sodium sulfate, etc. ) can promote the dissolution of protein. For example, adding concentrated inorganic salt solution to protein aqueous solution can reduce the solubility of protein and precipitate it from the solution, which is called salting out.
In this way, protein precipitated by salt can still be dissolved in water without affecting the original properties of protein, so salting out is a reversible process. Using this characteristic, protein can be separated and purified by salting out.
⑤ protein's degeneration.
Under the action of heat, acid, alkali, heavy metal salts and ultraviolet rays, protein will change its nature and condense. This condensation is irreversible and cannot be restored to the original protein protein. This change is called degeneration.
After denaturation, protein lost its original solubility and physiological function. Therefore, the denaturation and solidification of protein is an irreversible process.
The causes of protein's degeneration
Physical factors include: heating, pressure, stirring, oscillation, ultraviolet irradiation, ultrasonic wave, etc.
Chemical factors include: strong acid, strong base, heavy metal salt, trichloroacetic acid, ethanol, acetone and so on.
⑥ color reaction
Protein can react with many reagents. For example, if concentrated nitric acid is dropped into the egg white solution, the egg white solution will turn yellow. This is due to the color reaction between protein (containing benzene ring structure) and concentrated nitric acid. It can also be detected by biuret reagent, which will turn purple when it meets protein.
All landowners protein burning decomposition, will produce a special smell of burnt feathers.