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

Types and properties of collagen [2. P. 1865]

Types	Chain combination	Location
I	[α1(I)]2, α2	Skin, bone, tendon
II	[α1(II)]3	Cartilage
III	[α1(III)]3	tumor tissue
IV	[α1(IV)]3	Basal membrane

The synthesis of a polypeptide molecule in the collagen chain and the formation of its three-helix structure are widely covered in the scientific literature [2. S. 1864]. The structure of the collagen triple helix is formed from the spiral winding of all three formed α-chains, and the tropocollagen molecule is formed from its assembly. The tropocollagen molecule assembles into fibrillar fibers ranging in size from 10 nm to 300 nm, and fibrillar fibers accumulate to form collagen fibers ranging in size from 0.5 to 3 µm (Fig. 1). Biomaterials are produced on the basis of collagen, which forms fibrillar fibers.

The tropocollagen molecule has a size of 280 nm, a diameter of 1.4 nm and a molecular weight of about 300,000 daltons. Tropocollagen polypeptide chains are of the α-type, each of which consists of 1000-1040 amino acid residues [4. P. 301].

Fig. 1. Scheme of the three-helix structure of collagen (a), the assembled tropocollagen molecule (b), collagen fibrils (c) with a diameter of 10 to 300 nm, collagen fibers with a diameter of 0.5 to 3 μm (d) [2. P. 1865].

A structural feature of collagen is the formation of strong hydrogen bonds between the ON groups of hydroxyproline and bridging water molecules in triplets of the Gly-X-Hyp type.
Type I collagen is widely used in the production of biomaterials due to the absence of antigenic and immunogenic effects and non-toxicity [5. P. 1203]. However, it should be noted that there are data on the immunological effect of collagen. Such adverse effects are not caused by the collagen molecule itself, but by the presence of residual α-Gal or DNK molecules in it, which leads to acute immune reactions [6. P. 110].
Amino acid composition of collagen. Collagen has been found to be made up of over 19 different amino acids. This means that it has a specific amino acid content compared to other proteins (Table 2).