Progress and mechanism of breaking glycoconjugates by glycosidases in skin for promoting unhairing and fiber opening-up in leather manufacture.A review

The glycoconjugates,herein glyco-proteins,existing in animal skins are closely related to the effectiveness of unhairing and fiber opening-up.Glycosidases have been used in leather making processes to reduce pollutants and improve leather quality.But the selection of glycosidases is still blind because the related mechanisms are not well understood yet.Hence,the animal skin structures and glycoconjugates components,the advances in the methods and mechanisms of removing glycoconjugates related to unhairing and fiber opening-up in leather manufacture,the kinds,compositions,structures and functions of typical glycoconjugates in skin are summarized.Then the approaches to destroy them,possible glycosidases suitable for leather making and their acting sites are analyzed based on the recognition of glycoconjugates in skin and the specificities of glycosidases toward substrates.It is expected to provide useful information for the optimization of glycosidases and the development of new enzymes and the cleaner technologies of unhairing and opening up fiber bundles assisted by glycosidases.

Screening of additives to reduce grain damage risk on unhairing by proteinase K

Enzymatic unhairing is a cleaner strategy for leather-making.It is a potential alternative to the traditional hairburning process.However,several shortcomings,such as uncontrolled enzymatic reaction,and risk of grain looseness and damage have restricted the broad application of enzymatic unhairing.In this work,metal ions and organic additives were screened for lessening the hydrolytic activity of proteinase K to collagen fiber.Then,the selected additives were applied to the enzymatic unhairing process for bovine hide.The results showed that a suitable concentration of metal ions(Cu(Ⅱ),Fe(Ⅲ)and Al(Ⅲ))and organic additives(salicylate,laurate,adipate,gallate and epicatechin(ECG))could diminish approximately 35% of the hydrolytic activity of proteinase K to collagen fibers.Then,the additives were applied for the bovine hide enzymatic unhairing process.Hydroxyproline determination in the unhairing float shows that applying additives could reduce collagen hydrolysis.The morphology results showed that the grain damage could be significantly reduced with the addition of the screened additives in the proteinase K enzymatic unhairing system,whereas the addition of ECG and gallate significantly slowed down the unhairing speed.This outcome provides new potential to reduce the risk of grain damage in enzymatic unhairing process.

Collagenases and their inhibitors:a review

Hide and skin are complex tissue where the most abundant component is collagen.Matrix metalloproteinases and bacterial collagenases are two kinds of collagenases that can cleave the triple-helical domain of native fibrillar collagens.In this paper,the family members and domain composition of matrix metalloproteinases and bacterial collagenases are summarized.The catalytic mechanism of collagen hydrolysis by collagenases is described,and the methods adopted to date for investigating and regulating collagenases and their inhibitors are reviewed.Furthermore,the applications of collagenases and their inhibitors in biomedicine,food processing and the enzymatic unhairing process in the leather-making industry are presented.