Modification Of Protease Via Click Chemistry And Its Application In Wool Anti-felting Finishing

Felting of wool fabrics in washing process affects their wearability.The use of proteases for anti-felting finishing of wool is eco-friendly,energy-saving and efficient.However,due to the small molecular weight,hydrolysis of protease occurs inside the wool fibers,which results in the serious loss of fabric strength after finishing.In order to realize the purpose of preventing the felting of wool fabrics and improving fabric strength damage,it is necessary to modify protease to increase its molecular weight so as to restrict the hydrolysis of the proteases to the surface of the fibers,which will reduce the damage to the wool.Click chemistry is a new method for synthesizing new compounds simply and efficiently through the carbon-heteroatom bonds.It has the advantages including modularity,simple operation,mild reaction conditions,high selectivity,etc.Click chemistry has developed rapidly in areas such as surface modification,drug development,and biomedical sciences,so it can be used as a new method for enzyme modification technology.In this paper,protease was modified with monomethoxy polyethylene glycol(mPEG)via click chemistry.The structure changes of protease before and after modification were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE),fourier transform infrared spectroscopy(FTIR),circular dichroism and fluorescence spectroscopy.The effects of temperature and pH on the enzymatic properties as well as changes of enzymatic kinetics were investigated.The results showed that the molecular weight of mPEG-modified protease was higher than that of unmodified protease.The secondary structure was slightly changed.The decrease of Michaelis constant(K_m)means the affinity of protease to the substrate increased.The activity retention ratio of modified Savinase was 88%.The enzymatic properties of proteases before and after modification as functions of pH and temperature were similar.Based on above research,dextran was further used to modify the protease by click chemistry.The modification of protease was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE),circular dichroism and fluorescence spectroscopy.The enzymatic kinetics and the effects of temperature and pH on the enzymatic properties were studied.The results showed that the molecular weight of dextran-modified protease was significantly increased than that of mPEG-modified protease.The proportion of helix and turns structure decreased,while the proportion of strand and unordered structure increased.The K_m of protease increased after dextran modification,which means the affinity of protease to the substrate was reduced.The enzyme activity retention rate of dextran-modified Savinase was 85%.The enzymatic properties of native and modified protease still had a similar trend as the function of pH and temperature.The native protease,mPEG-modified protease and dextran-modified protease were used for anti-felting finishing of wool fabrics.Hydrolysis of modified Savinase was limited to the fiber surface.And the modified protease-treated wool fabrics could reach the machine-washable standard with decreased strength loss.Therefore,the modified protease has a greater prospect in the application of wool anti-felting finishing.