The Study On Efficient Enzymatic With Modified Cellulase Of Cellulose And Chitosan

In this study, Cellulase was modified with MW of5k,10k and20kmonomethoxyl-polyethylene glycol aldehyde (mPEG-ALD5k,10k,20k), MW of5k,10k and20k monomethoxyl-polyethylene glycol maleimide(mPEG-MAL5k) and MWof5k monomethoxyl-polyethylene glycol succinimide (mPEG-SPA5k), then sevenkinds of modified cellulase were obtained. The cellulase and modified cellulase werecharacterized by the determination of modification degree, FT-IR and Micro-FTIR.And their kinetic properties such as optimum reaction conditions, Kmand thermalstability were determined.Microcrystalline cellulose was degradated by natural cellulase and modifiedcellulases in the homogeneous system composed of NaOH/urea and microcrystallinecellulose. The concentration of reducing sugar was characterized by DNS to analysisthe degradation effect. The systematic investigation of reaction conditions on theenzymatic degradation were carried out and the optimum conditions were obtained.The results also suggested that the alkali resistance of modified cellulase increasedobviously.Chitosan was degradated by natural cellulase and modified cellulase in the ionicliquid [Gly]BF4system. The molecular weight of product was evaluated by ubbelohdeviscosity method to analysis the degradation effect. The experimental data showed thatthe degradation effect of modified cellulase was better than that of natural cellulase,and the Cell-ALD10K has the highest catalytic activity. This suggested that thecatalytic activity of modified cellulase was improved.In the ionic liquid [Gly]BF4system and HAC system, the degradation reaction of chitosan by Cell-ALD10K were studied. The molecular weight of products wasdetermined by ubbelohde viscosity method and the absorption spectrophotometrymethod. The influence of reaction conditions on the enzymatic hydrolysis wereinvestigated. The optimum reactions conditions were as follows: in ionic liquid[Gly]BF4system, pH5.0,12ml enzyme dosage, reaction temperature50℃, reactiontime5h, then the molecular weight of product separated out solution was1.21×104,the molecular weight of chitooligosaccharide in solution measured by absorptionspectrophotometry method was about1500, and the yield of chitooligosaccharidethrough calculated was76.36%.