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Proteins for Conditioning Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Fibrous proteins (protein chains arranged in parallel) include the water-swellable (but not soluble) structural proteins keratin, collagen, and elastin, major components of hair, skin, and connective tissue, respectively. Intermolecular crosslinks are common in these proteins, particularly those containing the monomer cysteine (R = -CH2-SH). When oxidized, two cysteines form one cystine linkage (-CH2-S-S-CH2-). Such bonds are responsible for hair's strength as well as its ability to be reconfigured, or "permanent waved."
Extraction of keratin from unhairing of bovine hide
Published in Chemical Engineering Communications, 2022
Franck da Rosa de Souza, Jaqueline Benvenuti, Michael Meyer, Hauke Wulf, Enno Klüver, Mariliz Gutterres
The amino acid profiles of both raw materials are similar (Figure 3). The most significant difference is observed in the sulfur containing amino acids, cysteine and cystine (Cys), and lanthionine (Lan). It has to be mentioned that during the acidic sample preparation for amino acid analysis, cysteine becomes oxidized forming cystine. Therefore, the measured value of cystine does not necessarily quantify the number of disulfide bonds in the hair sample but indicates the sum of the cysteine and cystine content of the sample. In the recovered hair, the cystine content is lower but lanthionine is higher compared to the hair sample. The lanthionine residue is formed from cystine during the alkaline processing. The higher content of lanthionine in the recovered hair powder explains the lower yield in the experiments with reducing agents.
Medical textiles
Published in Textile Progress, 2020
Whilst the keratin in the cortical cells contains a substantial proportion of the fibre’s cysteine, each of the outer layers of the cuticular cells contain progressively more and more, and being composed of very-highly, cross-linked protein the cuticular cells are therefore both physically hard and resist water penetration [18]. The cortex of the fibre in both cases is composed of the protein keratin which is typified by long helical protein chains cross-linked at regular intervals through the disulfide bonds in the amino acid cystine. The helical protein chains confer on wool its substantial extensibility, especially when wet, and the regular cross-linkages from cystine assist it to return to its original dimensions, again especially when wet, see for example, the CSIRO summary of wool structure [19].
Solid-phase synthesis of sulfur containing heterocycles
Published in Journal of Sulfur Chemistry, 2018
The reaction of cysteine was carried out with nitrophenyl carbonate derivative of Wang resin first by employing bis-(trimethylsilyl)-acetamide (BSA) to dissolve the amino acid. The thiol was treated with a number of halo-nitrobenzene derivatives. The cystine was formed in yields up to 25% during this step by dimerization of the resin-bound cysteine. This was suppressed by utilizing a 1,8-diazabicyclo[5.4.0]undec-7-ene base and strictly inert atmosphere. Alternatively, the tributyl phosphine was utilized for clean reduction of cysteine and further reacted with the halo-nitrobenzene derivative. The benzothiazepine derivative was synthesized by reducing the nitro group with tin-dichloride dihydrate and cyclization with EDC. The oxidation of sulfide to the sulfone was carried out with m-chloroperoxybenzoic acid for achieving the further diversity (Scheme 46) [81].