Ceratinum
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Ceratinum (e verbo Graeco κέρας, κέρατοςː 'cornu') -vel fortasse potius ceratina, quoniam plura sunt- est proteina fibrosa cytosceleti in ceratinocytis producta. E diametri magnitudine (circiter 10 nm) inter filamenta media ponitur. Ceratinum durum in animalium cornu, capillis, villis, lana, unguibus, pennis invenitur. Ceratinum mollius in cellulis vivis versatur. In strato superficiali cutis humanae (necnon aliorum mammalium) cellulae epitheliales epidermidis iam mortuae cumulantur, in quibus paene nihil nisi ceratinum valde compressum remanet. Illud impermeabile tegumentum totum corpus protegit tam adversus solis radios quam contra bacterias. Ceratina intracellularia (endoceratina) a ceratinis extracellularibus (extraceratina) distingui solent
De structura moleculari
[recensere | fontem recensere]
Molecula ceratini e dimero helicum α consistit. Nam in structura primaria ceratinorum aminoacida per septena repetuntur, ita ut aminoacida non polaria, hoc est hydrophoba, semper primum et quartum locum septenorum occupant. Ita duae helices per appendices hydrophobas sese conglutinant quae invicem adtrahant. Deinde plura dimera structuram aedificant rudentibus aut restibus manu factis similiorem. Haec aedificatio energiam non expendit. In alpha-ceratinis, quae in duris structuris versantur, multa cysteina reperiuntur, quae pontes sulphureos inter filamenta iungunt.
Mutationes geneticae in ceratino gravium morborum causa inveniuntur, exempli gratia in epidermolysi bullosa simplici, cum strata epithelii dehiscunt et vesiculae interveniunt.
Fontes
[recensere | fontem recensere]
- Charlotte Pratt et Kathleen Cornely, Essential Biochemistry, Wiley, 2018ː V.3. In versione Francogallica, De Boeck, 2019 pp.135-6
Plura legere si cupis
[recensere | fontem recensere]- Hermann H Bragulla et Dominique G Homberger, "Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia", Journal of Anatomy, 2009ː 516-559
- Robert G. Oshima, "Intermediate Filaments: A Historical Perspective", Experimental Cell Research, 2007: 1981–1994.
- Schweizer J, Bowden PE, Coulombe PA, et al. (July 2006). "New consensus nomenclature for mammalian keratins". J. Cell Biol. 174 (2): 169–74.
- Luca Tombolato, Ekaterina E. Novitskaya, Po-Yu Chen, Fred A. Sheppard, Joanna McKittrick, "Microstructure, elastic properties and deformation mechanisms of horn keratin", Acta biomaterialia, 2010ː 319-330
- Bin Wang, Wen Yang, Joanna McKittrick, Marc André Meyers, "Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration", Progress in materials science, 2016ː 229-238 [1]