From Big Medical Encyclopedia

FIBROYN — the protein of group of skle-roproteid formed by so-called spinning glands of insects (spiders, larvae of a mulberry and oak silkworm, etc.). T. represents insoluble fibrous protein of natural silk, in thread to-rogo it it is surrounded with sticky amorphous substance — protein the sericine making apprx. 1/3 fibers of natural silk. T. it was used in the biochemical researches having great theoretical and practical value during the studying of secondary structure of fibrous proteins (see) and conformations of peptide chains in molecules of proteins (see Conformation). Properties F. in many respects cause properties of natural silk, to-ry it is widely applied in surgical practice.

In glands of a silkworm (Bombyx mori) F. and sericine contain in a type of the concentrated viscous solution, in Krom of a molecule F. have no certain orientation. For the first time these molecules are guided at breakdown of the concentrated proteinaceous solution through an opening of gland, and then at extension which is formed and quickly stiffening thread legs of a worm. At extension between macromolecules F. the stabilizing hydrogen bindings are formed. Process of receiving an artificial silk reminds process of formation of silk thread a silkworm.

The major amino acids F. are glycine (see), alanine (see), serine (see) and tyrosine (see). On everyone two amino-acid the rest in a polypeptide chain F. regularly one rest of glycine is necessary.

Such structure of a polypeptide chain F. leads to formation of the so-called folded layer made of the parallel (anti-parallel) peptide chains oriented in opposite directions whereas, e.g., in a r-keratin (see Keratins) parallel peptide chains are oriented in one direction.

Bibliography: See bibliogr. to the station Skle-

of a roproteida.

N. G. Budkovskaya.