Keratins


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Related to Keratins: actin, hard keratin

Keratins

 

fibrous proteins whose fibers are a component of the horny layer of the epidermis and of hair, wool, feathers, scales, nails, horns, beaks, and hooves.

Keratins are insoluble in water and organic solvents and resistant to the action of proteolytic enzymes. It has been established by X-ray structural analysis that the polypeptide chains of keratins may be either twisted or elongated. The structure of nonelongate fibers (α-structure) is characteristic of the keratins of mammals; reptiles and birds have the elongate form (β-structure) as well (for example, in feathers). The insolubility of keratins is caused by the presence of transverse disulfide bonds between the polypeptide chains. The principal structural elements of α-keratins are cylindrical microfibrillae (diameter 75Å), which consist of spiraled protofibrillae twisted in pairs. The keratins of mammals are distinguished chiefly by their amino-acid composition, by the manner in which the microfibrillae are packaged, and by the amount of matrix (the high-sulfur protein in which they are embedded).

REFERENCES

Finean, Dzh. Biologicheskie ul’trastruktury. Moscow, 1970. (Translated from English.)
Freizer, R. “Keratiny.” In the collection Molekuly i kletki, issue 5. Moscow, 1970. (Translated from English.)

V. O. SHPIKITER

References in periodicals archive ?
Table 1: Distribution of major keratins. Keratin distribution in epithelia K5/14 Basal cell layer of both the keratinized and non-keratinized stratified epithelium K1/10 Keratinized epidermis K6/16 Spinous cell layer of keratinized mucosa K4/13 Intermediate layer of non-keratinized epithelium K19 Basal layer of non-keratinized epithelium K9 Suprabasal cells of palmar and plantar epidermis Keratin expression in gingival K5/14 Basal cell layer K19 Basal cell layer ofjunctional epithelium and gingival margin K8, 18, 13, 16, 19 Superficial layers ofjunctional epithelium K4, 13, 16 Superficial layer of gingival margin K1/10, K6/16 and Superficial layers of outer gingival K2p epithelium Distribution of keratin in the dorsal aspect of the tongue (Dale et al 1990).
Human hairs used as substrate for keratin extraction were collected from local hair salon in Maha Sarakham Province, Thailand.
The improvement in PASI scores in the tonsillectomy group was strongly correlated with a reduction in circulating, cross-reactive, skin-homing CLA+ CD8+ T cells responsive to 16 homologous M protein and skin keratin peptides.
The "Global Keratin Market 2019-2023" report has been added to ResearchAndMarkets.com's offering.
At this purpose, keratin extracted from wool has been studied as an attractive material for the development of films [2-4], sponges [4-7], scaffolds [4, 8] and nanofibers [4, 9-11] for specific applications in relation to their mechanical and chemical properties.
Keratin is a main constituent of skin, and its appendages like nails, hair, wool, feathers, hoofs, horns, beaks, scales of animal, and other epithelial coverings [4, 5].
Currently, physical and chemical treatments are used to increase the digestibility of feather keratin and the processed poultry feathers are used as animal feed stuff, fertilizers, glues, films and as the source of rare amino acids, such as serine, cysteine and proline (Raju and Divakar, 2013).
While other conventionally used substrates such as fibronectin and gelatin are obtained from animal sources and involve cumbersome and expensive extraction procedures, keratin can be easily extracted from human hair using a simple in house procedure, making it a cost effective substitute.
For SDS-soluble Hcy-keratin quantification, each SDS extract (300 [micro]l) was supplemented with 34 [micro]l 100% trichloroacetic acid and the precipitated keratin pellets were collected by centrifugation.
Their work has resulted in targeted nutritional interventions--highly bioavailable forms of collagen peptides and solubilized keratin, combined with biotin and silicon.
The first study, conducted in China, identified start-codon mutations in the KLHL24 gene in five patients, confirmed keratin 14 as the substrate of the protein, and established that KLHL24 mutations induce disproportionate ubiquitination and fragmentation of keratin 14.
HS KAPs are essential for the formation of hair shafts through their extensive disulfide bond cross-linking to the abundant cysteine residues of hair keratins or hydrophobic interactions with keratins [20-23].