Study On The Interaction Of Alkaline Protease With Surfactants And Protease' Application In Liquid Detergent

Laundry detergent has received more and more attention,because of its many advantages such as simple manufacture technology,energy conservation,convenient use,good solubility at low temperature,phosphate-free and so on.The liquid detergent has a deficiency,the poor decontamination.Adding enzyme to the detergent can solve this problem.But the stability of the enzyme in liquid detergent is an urgent problem to be solved for China's washing industry.The effects of surfactants commonly used in laundry detergent on protease were investigated in this paper.Surfactants we used were linear alkyl benzene sulfonate(LAS),sodium dodecyl sulfate(LS),alcohol ethoxy sulfate(AES),fatty alcoholpolyoxyethylene(AEOs)and alkylpolyglucosides(APGs).Results showed that anionic surfactants had strong deactivation effect on protease activity.The inhibitory effects of nonionic surfactants AEOs and APGs on alkaline protease activity were not obvious.The interaction mechanism between surfactants and alkaline protease were discussed by Dynamic light scattering(DLS)and Raman spectrum.DLS results showed in anionic surfactants solutions,Zeta potential values had more negative.Zeta potential of alkaline protease and alkaline protease in solutions of AEOs and APGs has small variation.Raman spectroscopy results showed that protease secondary structure(?-sheet,?-fold,random coil structure),hydrogen bonds,side chain conformations and local environments(tyrosine,tryptophan)were strongly influence by anionic surfactants.And the effect of nonionic surfactants on the conformation of the main chain and side chain of the alkaline protease is very small.In this paper,we studied the stability of alkaline protease,alkaline protease added stabilizer and the encapsulated alkaline protease in four kinds of laundry detergent at 20?and 40?.The results showed that activity of alkaline protease without stabilizer lost quickly in four laundry detergents.Add stabilizer to alkaline proteases can keep protease activity to some extent.Encapsulated alkaline protease can separate alkaline protease and water and surfactants in laundry detergent,it could maintain the activity of alkaline protease.The activities of encapsulated alkaline protease placed in 45 days were 87.7%,81.4%,77.5%and 52%,which were 3,9,38 and 7 times as much as that of alkaline protease without stabilizer,1.3,1.3,1.6 and 3 times as much as that of alkaline protease with stabilizer.At 40?,alkaline protease,alkaline protease added stabilizer and the encapsulated alkaline protease had the poor stability compared to at 20?.