Solubilization of keratins and functional properties of their isolates and hydrolysates

Sinkiewicz, Izabela; Staroszczyk, Hanna; Śliwińska, Agata

doi:10.1111/jfbc.12494

Cited by 39 publications

(30 citation statements)

References 103 publications

(113 reference statements)

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“…There are multiple thermochemical methods available to prepare hydrolysed keratin for various value-adding opportunities, with specific processes chosen depending on the end-use [4]. Thermochemical methods include solubilization of keratin in organic solvents, ionic liquids or by hydrothermal methods; oxidation or reduction of the disulphide bridges; disruption of the hydrogen bonds with compounds like urea; and acid or base hydrolysis.…”

Section: Thermochemical Methods Of Keratin Degradationmentioning

confidence: 99%

“…α-Keratin has an α-helix structure, which is stabilized by hydrogen bonding and the presence of multiple cysteines forming disulphide bridges. α-Keratin is characterized by a lower sulphur content compared to other keratins and a molecular mass of 60-80 kDa [4]. Hard α-keratin is the major protein of mammalian fibres, nails, hooves and horns.…”

Section: Keratin: a Complex And Strong Structurementioning

confidence: 99%

“…There is, however, an opportunity for livestock industries to produce higher value products from waste keratin. There are multiple thermochemical methods available to prepare hydrolysed keratin for various value-adding opportunities [4]. However, the use of peptidases endocuticle, which contains only low levels of sulphur-containing amino acids and constitutes the inner lining of the cuticle [8].…”

Section: Introductionmentioning

confidence: 99%

“…The two main types of keratins proteins are α-keratin and β-keratins. These two types are further divided into acidic or basic, soft or hard, and have different molecular weights [4,9,12,13]. The following section describes the complexity of the keratin structure, which provides insight into the resistance of keratin to hydrolysis.…”

mentioning

confidence: 99%

“…This review will concentrate on hard α-keratin and β-keratin, γ-keratins and the keratin-associated proteins, which are common to mammalian hair, bristles, wool, hooves, horns and feathers.α-Keratin has an α-helix structure, which is stabilized by hydrogen bonding and the presence of multiple cysteines forming disulphide bridges. α-Keratin is characterized by a lower sulphur content compared to other keratins and a molecular mass of 60-80 kDa [4]. Hard α-keratin is the major protein of mammalian fibres, nails, hooves and horns.…”

mentioning

confidence: 99%

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Challenges and Opportunities in Identifying and Characterising Keratinases for Value-Added Peptide Production

et al. 2020

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Keratins are important structural proteins produced by mammals, birds and reptiles. Keratins usually act as a protective barrier or a mechanical support. Millions of tonnes of keratin wastes and low value co-products are generated every year in the poultry, meat processing, leather and wool industries. Keratinases are proteases able to breakdown keratin providing a unique opportunity of hydrolysing keratin materials like mammalian hair, wool and feathers under mild conditions. These mild conditions ameliorate the problem of unwanted amino acid modification that usually occurs with thermochemical alternatives. Keratinase hydrolysis addresses the waste problem by producing valuable peptide mixes. Identifying keratinases is an inherent problem associated with the search for new enzymes due to the challenge of predicting protease substrate specificity. Here, we present a comprehensive review of twenty sequenced peptidases with keratinolytic activity from the serine protease and metalloprotease families. The review compares their biochemical activities and highlights the difficulties associated with the interpretation of these data. Potential applications of keratinases and keratin hydrolysates generated with these enzymes are also discussed. The review concludes with a critical discussion of the need for standardized assays and increased number of sequenced keratinases, which would allow a meaningful comparison of the biochemical traits, phylogeny and keratinase sequences. This deeper understanding would facilitate the search of the vast peptidase family sequence space for novel keratinases with industrial potential.Catalysts 2020, 10, 184 2 of 23 with keratinolytic activity for keratin hydrolysis protects the integrity of the keratin amino acids in most cases and allows control over the peptide size in the hydrolysate that is not readily achievable with other methods [5]. This degree of control allows the production of bespoke medical biomaterials, smart biocomposites, protein feed supplements with enhanced nutritional and bioactive properties as well as personal care products with enhanced functional and bioactive properties.Identifying peptidases with keratinolytic activity is an inherent problem associated with the search for new enzymes. Keratinase activity however appears to be dependent on the accessibility of the keratin substrate to the enzyme [6,7]. Thermochemical or biochemical treatment of the keratin, with emphasis on the reduction of the disulphide bond and disruption of other important bonds involved in the structural stability of keratin like isopeptide, hydrogen and glycolytic bonds [6,[8][9][10], appears to be the prerequisite for enzymatic hydrolysis. Sulphitolysis, which involves reduction of the disulphide bond in keratin, often acts synergistically with keratinases in nature [6,7]. Although destabilization of the keratin structure is a prerequisite for keratin hydrolysis, not all peptidases can hydrolyse keratin. Peptidases like trypsin, papain and pepsin cannot hydrolyse keratin as efficiently ...

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Section: Thermochemical Methods Of Keratin Degradationmentioning

confidence: 99%

Section: Keratin: a Complex And Strong Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Challenges and Opportunities in Identifying and Characterising Keratinases for Value-Added Peptide Production

et al. 2020

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Bioconversion of waste sheep wool to microbial peptone by Bacillus licheniformisEY2

Tuysuz

Özkan

Arslan³

et al. 2021

Biofuels Bioprod Bioref

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Peptones are among the most expensive culture components used in the cultivation of microorganisms. This study was performed to prepare a protein hydrolysate from sheep wool using a locally isolated keratinolytic bacterium Bacillus licheniformis EY2 (GenBank: MN809476), and to investigate the usability of the prepared hydrolysate as a peptone in a microbial medium. The optimum pH, temperature, and incubation time for wool hydrolysis and keratinolytic activity were determined as 7.0, 55 °C, and 6 days, respectively. Optimum concentrations of KH2PO4, MgSO4, and NaCl were determined as 1.5, 0.5, and 2 g/L, respectively. After the prepared hydrolysate was partially purified, it was converted to wool peptone (WP). The total protein, ash, carbohydrate, and lipid content of WP was found to be 82.7, 7.2, 0.1, and 0.2 g/100 g, respectively. Fourier transform infrared (FTIR) analysis of WP confirmed the formation of sulfoxide bonds (S=O), which indicated the breaking of disulfide bonds. When compared with commercial tryptone peptone (TP), WP was found to be superior for the cell growth performances of Esherichia coli, Bacillus subtilis, Staphylococcus aureus, Lactobacillus plantarum, Pediococcus pentosaceus, Candia albicans and Aspergillus niger. A protein hydrolysate (including wool protein hydrolysate) prepared via microbial hydrolysis was tested for the first time as a peptone source. The cost of WP is much lower than commercial peptones. At the same time, the method developed offers an environmentally friendly approach for the reduction of the amount of unutilized or waste sheep wool. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd.

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Valorization of Chicken Feather Waste: Fabrication of Keratin‐Chitosan Biofilms

et al. 2021

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According to scientists, keratin is one of the most abundant fibrous materials in nature after cellulose and chitin in the world. Several nature fibrous materials have a wide range of application starting from biomedical application to the construction sector, and especially the textile sector. The uses of natural fibers in these sectors are economical for increasing their specific properties, such as antibacterial properties, flexibility, tensile strength, shear strength, toughness, etc. This paper presented a new type of keratin‐chitosan biofilms with the separation of keratin from waste chicken feathers. The laboratory‐scale keratin extraction process was designed. The keratin extraction percentage of different lixiviants (NaOH; NaOH+Na2S; Na2S) were studied and compared each other to understand the reaction process. The chosen reaction parameters were lixiviant concentration, reaction time, and temperature in an attempt to figure out their effects on the extraction of keratin. The highest extraction value was achieved at 60 °C and 400 rpm for 6 h, and 0.5 M Na2S per 5 g of chicken feather powder. After obtaining keratin powder from the chicken feather powder, the keratin and chitosan powders were mixed in a certain ratio. Afterwards the polyvinyl alcohol was added into the mixture of keratin and chitosan at 100 °C until forming the biofilms. The properties and structure of the biofilms were characterized and antibacterial properties of films were examined. Owing to its enormous extraction performance using common and cheap chemicals and simple equipment at ambient conditions, the pile processing method has great promise for the keratin bio‐waste's industrially.

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Solubilization of keratins and functional properties of their isolates and hydrolysates

Cited by 39 publications

References 103 publications

Challenges and Opportunities in Identifying and Characterising Keratinases for Value-Added Peptide Production

Challenges and Opportunities in Identifying and Characterising Keratinases for Value-Added Peptide Production

Bioconversion of waste sheep wool to microbial peptone by Bacillus licheniformisEY2

Valorization of Chicken Feather Waste: Fabrication of Keratin‐Chitosan Biofilms

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