Structure of Wool Fibres: Isolation of an α- and β-Protein in Wool

Alexander, Peter; Earland, Christopher

doi:10.1038/166396a0

Cited by 124 publications

(40 citation statements)

References 7 publications

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“…This hypothesis follows from the assumption that keratinization in the wool follicle is a two-stage synthesis in which the proteins of the wool matrix (high-sulphur proteins) are the last to be synthesized (Mercer 1961). Downes, Sharry, and Rogers (1963) have already found supporting evidence for this hypothesis from the difference in the specific activity of the sulphur in the /X-and y-keratoses (oxidized low and high-sulphur proteins respectively) (Alexander and Earland 1950;Thompson and O'Donnell 1959) prepared from the urea-insoluble fraction of the wool roots. In the present work the reductive method of Harrap and Gillespie (1963) has been used because the proteins after alkylation are easier to characterize by physicochemical means.…”

Section: Introductionmentioning

confidence: 81%

A Study of the Proteins of the Wool Follicle

Downes¹,

Ferguson²,

Gillespie³

et al. 1966

Aust. Jnl. Of Bio. Sci.

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SummaryA study has been made of the incorporation at different levels in the developing fibre of 35S into the two main protein fractions of wool. The proteins have been studied as the S-carboxymethyl derivatives rather than as the oxidized derivatives previously investigated. The results obtained give further support for a mechanism of synthesis which involves two stages. However, the incorporation of some 35S into the low-sulphur fraction of the keratinized fibre only 24 hr after the injection of [35S]cystine is somewhat surprising and possible explanations for this have been considered. A detailed comparison has been made of the proteins extracted from the unkeratinized portions of wool roots by 8M urea with those which can be extracted from the keratinized residue with urea-thioglycollate. As might be expected the latter proteins were very similar to those isolated from wool itself. The group of urea-soluble, high-sulphur proteins was different in containing considerable amounts of protein lower in both molecular weight and sulphur content than the comparable fraction from the fully keratinized wool. The possibility is discussed that some of these urea-soluble, high-sulphur proteins may be precursors of those in the fully keratinized fibre, conversion taking place by a process of sulphur enrichment.

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Section: Introductionmentioning

confidence: 81%

A Study of the Proteins of the Wool Follicle

Downes¹,

Ferguson²,

Gillespie³

et al. 1966

Aust. Jnl. Of Bio. Sci.

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“…Reduction: by potassium thioglycollate in urea to obtain 80-97% keratin from horn, hoof, hair, and further by starch-gel electrophoresis into high-sulfur and lowsulfur fractions [16,64,65] Alkaline thioglycollate [68]: by sodium thioglycollate in the absence of oxygen at PH 11 to obtain 80-90% feather keratin [69] Oxidation: By treating wool with peracetic acid and dilute alkali [66] Combination of a disulfide bond-breaking reagent and a protein denaturant Sulfitolysis: By sodium bisulfite with urea and an oxidizing agent [67] in feather rachis may be correlated with the lack of helical secondary structure. Both exhibit very low content of histidine and methionine.…”

Section: A-keratin B-keratinmentioning

confidence: 99%

“…Table 4 lists the purification procedures developed to obtain keratin derivatives. For a-keratinous materials, reduction, oxidation and sulfitolysis methods have been used to generate satisfactory amounts of the derivatives [16,[64][65][66][67]; while for b-keratinous materials, which have not been as extensively investigated as a-keratin, alkaline thioglycollate and a combination of a disulfide bond-breaking reagent and a protein denaturant were described in literature [68,69]. There are also reports discussing degraded keratins produced by partial hydrolysis (with acid, alkali or enzymes) of wool, hair and feathers.…”

Section: Solubility and Amino Acid Compositionsmentioning

confidence: 99%

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Wang

Yang

McKittrick

et al. 2016

Progress in Materials Science

682

474

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a b s t r a c tA ubiquitous biological material, keratin represents a group of insoluble, usually high-sulfur content and filament-forming proteins, constituting the bulk of epidermal appendages such as hair, nails, claws, turtle scutes, horns, whale baleen, beaks, and feathers. These keratinous materials are formed by cells filled with keratin and are considered 'dead tissues'. Nevertheless, they are among the toughest biological materials, serving as a wide variety of interesting functions, e.g. scales to armor body, horns to combat aggressors, hagfish slime as defense against predators, nails and claws to increase prehension, hair and fur to protect against the environment. The vivid inspiring examples can offer useful solutions to design new structural and functional materials.Keratins can be classified as a-and b-types. Both show a characteristic filament-matrix structure: 7 nm diameter intermediate filaments for a-keratin, and 3 nm diameter filaments for b-keratin.Both are embedded in an amorphous keratin matrix. The molecular unit of intermediate filaments is a coiled-coil heterodimer and that of b-keratin filament is a pleated sheet. The mechanical response of a-keratin has been extensively studied and shows linear Hookean, yield and post-yield regions, and in some cases, a high reversible elastic deformation. Thus, they can be also be considered 'biopolymers'. On the other hand, b-keratin has not been investigated as comprehensively. Keratinous materials are strain-rate sensitive, and the effect of hydration is significant.Keratinous materials exhibit a complex hierarchical structure: polypeptide chains and filament-matrix structures at the nanoscale, Progress in Materials Science 76 (2016) 229-318 Contents lists available at ScienceDirect Progress in Materials Sciencej o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / p m a t s c i organization of keratinized cells into lamellar, tubular-intertubular, fiber or layered structures at the microscale, and solid, compact sheaths over porous core, sandwich or threads at the macroscale. These produce a wide range of mechanical properties: the Young's modulus ranges from 10 MPa in stratum corneum to about 2.5 GPa in feathers, and the tensile strength varies from 2 MPa in stratum corneum to 530 MPa in dry hagfish slime threads. Therefore, they are able to serve various functions including diffusion barrier, buffering external attack, energy-absorption, impact-resistance, piercing opponents, withstanding repeated stress and aerodynamic forces, and resisting buckling and penetration.A fascinating part of the new frontier of materials study is the development of bioinspired materials and designs. A comprehensive understanding of the biochemistry, structure and mechanical properties of keratins and keratinous materials is of great importance for keratin-based bioinspired materials and designs. Current bioinspired efforts including the manufacturing of quill-inspired aluminum composites, animal horn-inspired SiC composites, and feather-i...

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“…The acid-insoluble fractions are referred to as a-keratose and (a-X)-keratose respectively. This nomenclature does not conflict with the terms introduced by Alexander and Earland (1950) and now generally adopted.…”

Section: (A) Fractionation and Nomenclature Of Extracted Wool Proteinsmentioning

confidence: 99%

Studies on Oxidized Wool VI. Interactions Between High- and Low-'Sulphur Proteins and their Significance in the Purification of Extracted Wool Proteins

O'donnel¹,

Thompson²

1962

Aust. Jnl. Of Bio. Sci.

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SummaryThe amounts of protein extractable from wool following oxidation with performic acid, and the yields of high. sulphur (y·keratose) and low· sulphur (",-keratose) fractions have been shown to depend markedly on the conditions of dialysis used to remove excess performic acid reagent. The results are explained by assuming that denaturation occurs in warm dilute formic acid. Following denaturation in this way, or following exposure to solutions of trichloroacetic acid or to alkali at pH 11, the extracted proteins are more readily separated into high. and low· sulphur fractions. It is postulated that contaminant high. sulphur protein is responsible, in part, for the chromatographic heterogeneity and for the variation in amino acid composition of separated low· sulphur proteins. Binding of this high· sulphur contaminant protein fraction to the low·sulphur proteins is shown to be by secondary valence bonds. The percentage of high. sulphur proteins in wool is higher than the estimates of earlier workers.

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Structure of Wool Fibres: Isolation of an α- and β-Protein in Wool

Cited by 124 publications

References 7 publications

A Study of the Proteins of the Wool Follicle

A Study of the Proteins of the Wool Follicle

Keratin: Structure, mechanical properties, occurrence in biological organisms, and efforts at bioinspiration

Studies on Oxidized Wool VI. Interactions Between High- and Low-'Sulphur Proteins and their Significance in the Purification of Extracted Wool Proteins

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