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Keratinase

About: Keratinase is a research topic. Over the lifetime, 903 publications have been published within this topic receiving 21476 citations.


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Journal ArticleDOI
TL;DR: Keratinases stand out among proteases since they attack the keratin residues and hence find application in developing cost-effective feather by-products for feed and fertilizers and their prospective application in the challenging field of prion degradation would revolutionize the protease world in the near future.
Abstract: Microbial keratinases have become biotechnologically important since they target the hydrolysis of highly rigid, strongly cross-linked structural polypeptide “keratin” recalcitrant to the commonly known proteolytic enzymes trypsin, pepsin and papain. These enzymes are largely produced in the presence of keratinous substrates in the form of hair, feather, wool, nail, horn etc. during their degradation. The complex mechanism of keratinolysis involves cooperative action of sulfitolytic and proteolytic systems. Keratinases are robust enzymes with a wide temperature and pH activity range and are largely serine or metallo proteases. Sequence homologies of keratinases indicate their relatedness to subtilisin family of serine proteases. They stand out among proteases since they attack the keratin residues and hence find application in developing cost-effective feather by-products for feed and fertilizers. Their application can also be extended to detergent and leather industries where they serve as specialty enzymes. Besides, they also find application in wool and silk cleaning; in the leather industry, better dehairing potential of these enzymes has led to the development of greener hair-saving dehairing technology and personal care products. Further, their prospective application in the challenging field of prion degradation would revolutionize the protease world in the near future.

571 citations

Journal ArticleDOI
TL;DR: Keratinases are exciting proteolytic enzymes that display the capability to degrade the insoluble protein keratin and their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling.
Abstract: Keratinases are exciting proteolytic enzymes that display the capability to degrade the insoluble protein keratin. These enzymes are produced by diverse microorganisms belonging to the Eucarya, Bacteria, and Archea domains. Keratinases display a great diversity in their biochemical and biophysical properties. Most keratinases are optimally active at neutral to alkaline pH and 40–60°C, but examples of microbial keratinolysis at alkalophilic and thermophilic conditions have been well documented. Several keratinases have been associated to the subtilisin family of serine-type proteases by analysis of their protein sequences. Studies with specific substrates and inhibitors indicated that keratinases are often serine or metalloproteases with preference for hydrophobic and aromatic residues at the P1 position. Keratinolytic enzymes have several current and potential applications in agroindustrial, pharmaceutical, and biomedical fields. Their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling.

388 citations

Journal ArticleDOI
TL;DR: The purified keratinase hydrolyzes a broad range of substrates and displays higher proteolytic activity than most proteases and is a useful enzyme for promoting the hydrolysis of feather keratin and improving the digestibility of feather meal.
Abstract: A keratinase was isolated from the culture medium of feather-degrading Bacillus licheniformis PWD-1 by use of an assay of the hydrolysis of azokeratin. Membrane ultrafiltration and carboxymethyl cellulose ion-exchange and Sephadex G-75 gel chromatographies were used to purify the enzyme. The specific activity of the purified keratinase relative to that in the original medium was approximately 70-fold. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and Sephadex G-75 chromatography indicated that the purified keratinase is monomeric and has a molecular mass of 33 kDa. The optimum pH and the pI were determined to be 7.5 and 7.25, respectively. Under standard assay conditions, the apparent temperature optimum was 50°C. The enzyme is stable when stored at −20°C. The purified keratinase hydrolyzes a broad range of substrates and displays higher proteolytic activity than most proteases. In practical applications, keratinase is a useful enzyme for promoting the hydrolysis of feather keratin and improving the digestibility of feather meal. Images

363 citations

Journal ArticleDOI
TL;DR: A serine protease from the keratin-degrading Streptomyces pactum DSM 40530 was purified by casein agarose affinity chromatography and showed high stereoselectivity and secondary specificity with different synthetic substrates.
Abstract: A serine protease from the keratin-degrading Streptomyces pactum DSM 40530 was purified by casein agarose affinity chromatography. The enzyme had a molecular weight of 30,000 and an isoelectric point of 8.5. The proteinase was optimally active in the pH range from 7 to 10 and at temperatures from 40 to 75 degrees C. The enzyme was specific for arginine and lysine at the P1 site and for phenylalanine and arginine at the P1' site. It showed a high stereoselectivity and secondary specificity with different synthetic substrates. The keratinolytic activity of the purified proteinase was examined by incubation with the insoluble substrates keratin azure, feather meal, and native and autoclaved chicken feather downs. The S. pactum proteinase was significantly more active than the various commercially available proteinases. After incubation with the purified proteinase, a rapid disintegration of whole feathers was observed. But even after several days of incubation with repeated addition of enzymes, less than 10% of the native keratin substrate was solubilized. In the presence of dithiothreitol, degradation was more than 70%.

344 citations

Journal ArticleDOI
TL;DR: The use of keratinases to enhance drug delivery in some tissues and hydrolysis of prion proteins arise as novel outstanding applications for these enzymes.
Abstract: Keratin-rich wastes in the form of feathers, hair, nails, and horn are highly available as byproducts of agroindustrial processing. The increased needs for energy conserving and recycling, summed with the huge increase in poultry industry, have strongly stimulated the search for alternatives for the management of recalcitrant keratinous wastes. Keratinases, which are produced by several bacteria that have been often isolated from soils and poultry wastes, show potential use in biotechnological processes involving keratin hydrolysis. Although these isolates are mostly restricted to the genera Streptomyces and Bacillus, the diversity of keratinolytic bacteria is significantly greater. Bacterial keratinases are mostly serine proteases, although increased information about keratinolytic metalloproteases, particularly from Gram-negative bacteria, became available. These enzymes are useful in processes related with the bioconversion of keratin waste into feed and fertilizers. Other promising applications have been associated with keratinolytic enzymes, including enzymatic dehairing for leather and cosmetic industry, detergent uses, and development of biopolymers from keratin fibers. The use of keratinases to enhance drug delivery in some tissues and hydrolysis of prion proteins arise as novel outstanding applications for these enzymes.

284 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202334
202281
202150
202052
201942
201844