The Biological Characteristics Of The Protein In Wheat Straw And Its Influence On Cellulase Activity

Wheat straw is the feedstock of second generation ethanol,the low cellulose hydrolysis rate has been the key restricting factor in its business operation. Therefore this study research on protein in long-term room temperature storage wheat straw in according to the actual situation of industrial production, explore its effect on cellulase activity, the results were as follows:1) After long-term storage at room temperature, the wheat straw protein yield remaining approximately3.24%, a large part of protein has degradated during storage. SDS extraction buffer, NaOH extraction buffer and NaCl extraction buffer were used on the extract of proteins, result show SDS extraction buffer get the maximum rate of protein extraction.2) Optimization through single factor and orthogonal experiments of protein extraction, optimal conditions for the extraction time was12h, extraction temperature50℃, the solid-liquid ratio of1:20mg/mL, the maximum extraction rate is21.76±0.01%. By SDS-PAGE found protein molecular weight were18KD,22KD,32KD and40KD, respectively.3) Study on enzymatic hydrolysis effect of wheat straw which had protein removed, protein removal methods were:(a) protein extraction;(b) protein hydrolysis;(c) untreated.Optimal condition for protease is:protease dosage100mg, solid-liquid ratio1:25, hydrolysis temperature45℃, hydrolysis pH3.0, hydrolysis time12h. Contrast with residual amount of protein of three protein removal methods found:(b) protein hydrolysis>(a) protein extraction>(c) untreated. Through single factor test and orthogonal test their maximum rate of cellulose hydrolysis were:proteolytic sample56.23%, protein extraction sample49.17%, untreated sample35.01%, indicating that protein removal and cellulose hydrolysis rate is positively correlated, the presence of proteins inhibited the process of cellulose hydrolysis.4) The extracted protein does not have cellulase activity but when take together with cellulase it shows inhibition, when protein concentration in the reaction system is1.2mg/ml FPA and endoglucanase activity inhibition rate of up to9.78%and52.42%, while it having a promoting effect on the P-glucosidase enzyme, when the solution system protein concentration is1.2mg/ml P-glucosidase activity increased by71.44%.5) Experiment on loading sequence of protein and cellulase can clearly know which ingredient affect on cellulose or cellulase. The result is when the protein firstly integrate with cellulase show more inhibition on enzymatic hydrolysis, it imply that the protein may occupy the cellulase enzyme center sites, thereby reducing the cellulase activity.