發(fā)布時間：2017-12-28 22:22

  本文關鍵詞：基于樹枝狀聚合物復合磁性納米材料的制備表征及其固定化纖維素酶的應用研究　出處：《江蘇大學》2017年碩士論文　論文類型：學位論文

  更多相關文章： 纖維素酶 四氧化三鐵納米粒子 氧化石墨烯 四臂聚乙二醇胺 固定化酶

【摘要】：纖維素是最豐富的可再生和可生物降解的聚合物。自然界里的纖維素年產量預計為1011 1012噸,雖然有如此多的纖維素來源,但是人們對于這種生物質資源的利用不是很高。纖維素酶是生物來源的催化劑,在溫和條件下具有較高的選擇性、特異性。但是由于纖維素酶的工作條件比較苛刻,在催化水解的過程中容易失去活性。因此纖維素酶的催化水解效率不高。由于固定化酶在較溫和的pH值、溫度、壓力條件下進行催化,有著高活性和無與倫比的選擇性,酶的固定化變的越來越重要。本文討論了兩種復合材料固定化纖維素酶,一種是四臂型聚乙二醇樹枝狀聚合物修飾在四氧化三鐵磁性納米粒子的上面。第二種是接枝兩種不同臂長的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面。本文選定了以蛋白載量,固定化酶的活力,比活力為衡量標準,討論了加酶量、時間、溫度三個條件對固定化纖維素酶的影響。又比較了游離酶與固定化纖維素酶的酶學性質,另外還比較兩種不同臂長的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶的酶學性質。主要是從最適最適pH、溫度、米氏常數、熱穩(wěn)定性、重復使用穩(wěn)定性以及貯藏穩(wěn)定性這幾個方面研究其酶學性質。研究結果表明:游離酶的催化反應最適溫度為45℃,而固定化酶的為50℃,游離酶的pH為5,固定化酶催化最適pH為4。四臂型聚乙二醇樹枝狀聚合物修飾在四氧化三鐵磁性納米粒子固定化纖維素酶、接枝分子接枝分子量5 K的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶、接枝分子量10 K的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶的米氏常數分別是11.9471 g/L,3.0411 g/L,1.6220 g/L。固定化酶在熱穩(wěn)定性、重復使用穩(wěn)定性、其貯藏穩(wěn)定性都比游離纖維素酶的好。最后做了三種酶的催化水解應用實驗,發(fā)現(xiàn)接枝分子量10 K的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶的催化效果比接枝分子接枝分子量5 K的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶好,接枝分子接枝分子量5 K的四臂型聚乙二醇樹枝狀聚合物修飾在磁性氧化石墨烯表面固定化纖維素酶的催化效果比四臂型聚乙二醇樹枝狀聚合物修飾在四氧化三鐵磁性納米粒子固定化纖維素酶效果好。
[Abstract]:Cellulose is the most abundant renewable and biodegradable polymer. The annual yield of cellulose in nature is estimated to be 10111012 tons. Although there are so many cellulose sources, the utilization of this biomass resource is not very high. Cellulase is a catalyst for biological origin, which has high selectivity and specificity under mild conditions. However, because of the harsh working conditions of cellulase, it is easy to lose its activity during the process of catalytic hydrolysis. Therefore, the efficiency of the catalytic hydrolysis of cellulase is not high. Immobilized enzyme is highly active and unequalled under mild pH value, temperature and pressure. Immobilization of enzyme is becoming more and more important. In this paper, two kinds of composite immobilized cellulase are discussed, one is the four arm polyethylene glycol dendrimer modified on magnetic iron oxide nanoparticles. The second is the grafting of two different arm length four arm polyethylene glycol dendrimers on the surface of magnetic graphene oxide. In this paper, protein loading, immobilized enzyme activity and specific activity were selected as criteria. The effects of three conditions, enzyme dosage, time and temperature on immobilized cellulase were discussed. The enzymatic properties of free enzyme and immobilized cellulase were compared. In addition, two different arm length four arm polyglycol dendrimers modified on the surface of magnetic graphene oxide were applied to immobilize cellulase. The properties of the enzyme are studied mainly from the most suitable and optimum pH, temperature, Michaelis constant, thermal stability, reuse stability and storage stability. The results show that the optimum temperature for the catalytic reaction of the free enzyme is 45, while the immobilized enzyme is 50, the pH of the free enzyme is 5, and the optimum pH of the immobilized enzyme is 4. Four arm type peg dendrimers modified Fe3O4 magnetic nanoparticles in immobilization of cellulase, the grafted molecular weight polyethylene glycol graft four arm type dendrimers 5 K modified in four arm type polyethylene glycol dendrimer magnetic graphene oxide surface immobilized cellulase, grafted with a molecular weight of 10 K in the modified Michaelis constant magnetic graphene oxide surface immobilized cellulase were 11.9471 g/L, 3.0411 g/L, 1.6220 g/L. The immobilized enzyme is better in thermal stability, reuse stability and storage stability than that of free cellulase. Finally the application experiment of three kinds of enzyme catalyzed hydrolysis, found four arm type polyethylene glycol dendrimer four arm type dendrimer grafted polyethylene glycol 10 K molecular weight modified on the surface of graphene oxide catalytic effect of magnetic immobilized cellulase than grafted graft molecular weight of 5 K on the surface of graphene oxide modified magnetic immobilized cellulase, four arm type dendrimer grafted polyethylene glycol grafted a molecular weight of 5 K modified on the surface of graphene oxide catalytic effect of magnetic immobilized cellulase than polyethylene glycol four arm type dendritic polymer modified Fe3O4 magnetic nanoparticles in immobilized cellulase effect.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：Q814.2;TB383.1

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