Mechanism Of No-productive Adsorption Of Cellulase To Dehydrogenation Polymer

Bioethanol is a renewable and clean fuel that can alleviate the pressure of petrochemical energy to some degree.It is getting more and more attention from the outside world because it is beneficial to the environment.Cellulase digestion is one of the most important steps in bioethanol production,but lignin in biomass feedstock can block cellulase contact with cellulose.At present,it is generally believed that the no-productive adsorption of lignin on cellulase is an obstacle to the commercialization of bioethanol.Due to the complexity of the lignin structure,limited results are currently available.In order to explain the effect of lignin on cellulase hydrolysis,this study used a lignin model to study its mechanism of no-productive adsorption of cellulase.The research contents are as follows:?1?Synthesis of three lignin precursors.In this study,p-hydroxybenzaldehyde,vanillin and syringaldehyde were used as starting materials to synthesize the precursors of lignin to p-glucocoumaryl alcohol,coniferin and syringin.The yields were 22.21%,46.29%and 35.75%,respectively.The structure of the product were confirmed by melting point detection,FT-IR,UV and ¹³C NMR analysis.?2?Synthesis of lignin dehydrogenation polymer?DHP?.The dehydrogenation polymer?DHP?were prepared from the three kinds of precursors by Zutropfverfahren?ZT?and Zulaufverfahren?ZL?with?-glucosidase,peroxidase and glucose oxidase.The DHPs were characterised by GPC,FT-IR,UV and NMR.The results showed that both ZT and ZL DHPs were close to the synthesis conditions of lignin in natural plants,and the structure had the characteristic structure of lignin.The ZL DHP had a lower average Mw,but the content of?-5,?-?and the phenolic hydroxyl group was high;and the Mw of ZT DHP was high,due to the higher content of?-O-4 in the main chain structure of lignin in the structure.?3?Different types of DHP were mixed with cellulase for adsorption experiments.The binding strength was G-DHP>H-DHP>S-DHP.There was a linear positive correlation between phenolic hydroxyl content and maximum adsorption capacity in DHP.And there was a negative correlation between PDI and binding strength in DHP.In the enzymatic hydrolysis experiment,the inhibition intensity of different types of DHP on avicel cellulose enzymatic hydrolysis was G-DHP>H-DHP>S-DHP.At the same time,the results showed that the smaller the molecular weight of DHP,the stronger the inhibition of cellulase enzymatic hydrolysis;the more?-5 content and phenolic hydroxyl content,the stronger the inhibition of cellulase enzymatic hydrolysis.In the desorption experiment,it was found that cellulase can be released by the buffer and remained enzyme activity,so it was presumed that DHP and cellulase were mainly combined by physical means such as hydrophobic interaction and electrostatic action.