Heparin sodium is a natural anticoagulant substance containing sulfuric acid group of sticky polysaccharide. Heparin is a collective name for a cluster of acidic mucopolysaccharide compounds of varying molecular weight sizes. Heparin has linear chain molecules consisting of hexosaccharide or octosaccharide repeat units with molecular weights ranging from 3,000 to 30,000Da, with an average molecular weight of about 15,000Da.

　　Heparin is widely present in the liver, lung and intestinal mucosa of mammals, and it is usually combined with protein to form complex. Heparin, a mucopolysaccharide containing sulfuric acid, amino acid and aldose acid, can be separated by enzymolysis protein. At pH8-9, with negative charge, it can be ion exchanged with anion exchanger for crude separation, and the polysaccharide solution is precipitated in high concentration ethanol for purification.

　　Heparin is combined with other mucopolysaccharides to form a complex with proteins in tissues. Therefore, the preparation process of biochemical heparin includes two steps: extraction of heparin protein complex, dissociation and separation and purification of heparin. Heparin molecule contains sulfuric acid group and carboxyl group, is a strong acid, polyanion, can react with cation to form salt. These cations include metallic cations: Ca2+,Na+,K+, organic bases of long-chain pyridine compounds such as cetylpyridine chloride (CPC), strychnine, basic dyestuf-azure A, and cationic surfactants (long-chain quaternary ammonium salts) such as cetyltrimethyl ammonium bromide; Cation exchange agent and positively charged protein such as spermatic 0 protein. The N-sulfate group in the structure of Chaoyang biochemical heparin is closely related to the anticoagulant effect, and its anticoagulant activity will be reduced if it is destroyed. N-sulphate groups are sensitive to acid hydrolysis and are fairly stable under alkaline conditions. The free hydroxyl group in the heparin molecule is esterified, such as sulfuration, and the anticoagulant activity also decreases, while the acetylation does not affect its anticoagulant activity. Sodium heparin is white or white powder, odorless, tasteless, moisture absorption, easily soluble in water, insoluble in ethanol, acetone, dioxane and other organic solvents.

　　Insufficient alkalinity results in acidic extract, and heparin will be destroyed rapidly under high temperature. Excessive heating will cause early coagulation of protein, which will affect the decomposition and dissolution of heparin. Based on the characteristic of proteolytic enzyme, combined with the method of adjusting acid and removing protein by oxidation, the method of removing protein by enzyme was adopted. The method could not affect the total titer of heparin when removing protein. In order to prevent the deactivation of heparin, sodium bisulfite was added as a protective agent during the process of acid adjustment and protein removal. The protein was removed by centrifugation at low temperature.