Получение товаров из кожи животных для медицинского применения и определение химического состава getting goods from animal skin for medical use and determination of chemical composition ibrohimjon Rahmonovich Asqarov

Table 2
Amino acid composition of collagen [7. P. 49]

Amino acids	Quantity,%	Amino acids	Quantity, %
Lysine	2,60	Alanine	10,93
Histidine	0.42	Valine	2.02
Asparagine	4.45	Methionine	0,61
Aspartate	4.90	Isoleucine	1.36
Threonine	1.87	Leucine	2,66
Serine	3,87	Tyrosine	0.52
Glutamine	7.19	Phenylalanine	1.31
Proline	11.82	Hydroxyproline	9.21
Glycine	33.50	Hydroxylysine	0.76

From the data presented in table. 2, it can be seen that the amount of proline and hydroxyproline in collagen differs significantly from the amount in other proteins. In addition to amino acids, collagen also contains polysaccharides (up to 2%) and monosaccharides (less than 1%). The presence of 35% glycine and about 11% alanine in collagen means that they are significantly different from the amount of protein known to most.

Proline and 4-hydroxyproline do not contain such amounts in protein, except for collagen and elastin. Collagen-containing proline is found mainly in the glycine-proline-X chain, while basic X can be hydroxyproline or alanine. Collagen amino acids do not contain cystine and tryptophan. The presence of oxyproline and oxylysin significantly distinguishes it from other proteins of a living organism (these amino acids are not found in other proteins), the role of these amino acids in biological processes is very large. The stability of the three-helix structure of the collagen molecule is enhanced by mutual covalent and hydrogen bonds of oxylysine and lysine residues in the molecule [8. P. 64].
Collagen non-toxicity, bioavailability and bioactivity of collagen protein, it is widely used in medicine and pharmaceuticals.
To isolate natural collagen from the skin of cattle, processes such as its purification from satellite biopolymers and dissolution in weak organic acids are carried out [9. S. 42]. Alkaline, acid and enzymatic hydrolysis methods are also used to extract collagen. The skin of cattle is purified from globular proteins, proteoglycans and glycoproteins by alkaline-salt hydrolysis. Research in the field of collagen extraction was carried out by foreign scientists. The water mass of collagen obtained by them was dissolved in organic acids and drugs used in medicine were developed [10. P. 14; 11. P. 29; 11.P. 43]. In addition, a number of studies have been carried out in the republic on the isolation of collagen from the skin of cattle, which developed a “method for obtaining a collagen substance that retains its natural structure by alkaline-salt hydrolysis [12. P. 19]. The authors studied the processes of obtaining collagen substance, such as alkaline-salt hydrolysis of the skin, neutralization, homogenization of the collagen mass and dehydration of the aqueous collagen mass [13. P. 5]. In the process of collagen dehydration, an aqueous mass was obtained containing 5.5-6.2% collagen, depending on the time of the second hydrolysis. However, this aqueous collagen mass has disadvantages such as low flexibility in the production of a biopolymer film and difficulty in shaping.
The aim of the study was to select the second hydrolysis time of the separation of the water mass of collagen to obtain a biopolymer film by the alkaline-salt hydrolysis method. And determine their physico-chemical parameters.