SCLEROPROTEIDS (Greek skleros firm, dense + protos first + eidos look; synonym scleroproteins) — fabric and cellular proteins. Together with myofibrillar proteins (see. Muscular tissue, biochemistry of muscular tissue ) Pages make wider group of fibrous proteins (see). Pages are steady against action of nonspecific peptide-hydrolases (see).
The general idiosyncrasy of S. is existence in their molecules, in addition to peptide bonds, the developed system inside - and intermolecular bonds. This communication is provided not only chemical resistance, but also high structural stability of macromolecules C. and their supermolecular features (e.g., fibers) that p defines their high mechanical strength. In total S. badly rastvorima in water and neutral salt solutions. The main function C. in a human body and animals is structural and mechanical function. Especially brightly it is expressed at S. of a mesenchymal origin; at intersticial kollagen — kollagen of types I, II and III (see. Collagen ) and at elastin (see); collagenic and elastic fibers are localized in intercellular substance connecting fabric (see). To elastin on mechanical characteristics it is similar rezilin — protein of insects.
Page of an epithelial origin — keratins (see), the skin which are structural proteins of periblasts, a hair, nails, perform protective and mechanical function.
Nek-rye S. differentiations of fabrics and a morphogenesis of bodies play an important role in processes of intercellular interactions, interactions of cells with intercellular substance. S. of basal membranes are in this respect especially active (see. Basal membrane ) — kollagena of type IV and steady against action collagenases (see) collagen 7S, and also the laminin synthesized by epithelial cells and representing a high-molecular glycoprotein (see. Glycoproteins ). Pages of basal membranes take active part in epithelial and mesenchymal interactions.
In interaction of connective tissue cells among themselves and with structures of intercellular substance the big role belongs pericellular collagen (a kollagena of type V) and to glycoproteins to the fibronectin localized on a cellular membrane of fibroblasts and a hondronektin, to-ry is on a membrane of chondrocytes.
Treat S. also fibroin — insoluble protein of silk, spongin — protein from sea sponges, gorgonin and anti-patinas — proteins of corals, flagellin — protein from flagellums of bacteria.
Bibliography: The Slutsk L. I. Biokhimiya normal and patholologically the changed connecting fabric, II., 1969; Comprehensive biochemistry, ed. by M. Flor-kin a. E. H. Stotz, v. 26, p. 633, Amsterdam a. o., 1972; Fibrous proteins, scientific, industrial and medical aspects, ed. by D. A. D. Parry a. L. K. Creamer, v. 1—2, L. — N. Y., 1979 — 1980.
L. I. Slutsky.