2010-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/711934摘要：聚木糖&#37238;為主要的半纖維分解酵素，可廣泛應用於食品、飼料、造紙、生質酒精及農業廢棄物處理等。然而半纖維素的組成與結構極為複雜，其完全水解需仰賴多種酵素共同作用，僅利用單一酵素水解效果有限。因此，雙功能半纖維分解酵素的使用將可加速半纖維素的水解及減少酵素的使用量，對生產成本的降低有極大助益。反芻動物的瘤胃是一個厭氣和高滲透壓的特殊環境，反芻動物本身的消化道因缺乏纖維分解酵素，必須仰賴消化道中的瘤胃微生物分泌相關酵素幫助纖維的分解消化，以提供動物所需的能量，因此瘤胃微生物演化成具有高度分解纖維素和半纖維素能力的族群，成為目前纖維分解酵素的潛力分離源。瘤胃中的絕對厭氧真菌更被證實其產生的纖維分解酵素活性遠比一般好氣性微生物高，而使得瘤胃厭氧真菌成為纖維分解酵素的開發潛力來源。本計畫擬針對瘤胃真菌之雙功能纖維分解酵素-乙醯聚木糖酯&#37238;/聚木糖&#37238;XynS20E進行研究，除探討全長型及截斷型XynS20E重組蛋白質的各結構區活性、酵素動力學、最適作用條件等酵素基本特性外，並將利用X射線結晶分析法針對該酵素及其與受質所形成複合物之晶體結構進行研究，亦將利用高效表達系統進行全長型及截斷型XynS20E的大量表達以評估其應用於飼料之可行性。<br> Abstract: Xylanases are fast becoming a major group of industrial enzymes due to their biotechnological utility and potential application in a range of industrial processes, such as biobleaching in the paper and pulp industry, bioconversion of lignocellulosic material and agro-wastes to fermentative products, clarification of juices, and improvement in the consistency of beer and the digestibility of animal feed stock. As plant cell walls are structurally complex, a cocktail consisting of bi- and multi-functional xylanases and xylan debranching enzymes is most desired combination for the efficient utilization of these complex materials. The natural diversity of enzymes provides some candidates with evolved bi-functional activity. Rumen fungi are able to degrade the most-resistant plant cell-wall polymers, thus, the rumen fungal population represents a rich and underutilized source of fibrolytic enzymes with tremendous potential for industrial and agricultural applications. In this study, a bi-functional acetylxylan esterase/xylanase enzyme XynS20E from rumen fungus Neocallimastix patriciarum will be investigated. The recombinant full-length and truncated XynS20E will be purified to investigate their characteristics, such as specific activity, substrate specificity, enzyme kinetics, and the optimal conditions for the highest enzyme activity. The three-dimensional structures of the full-length and truncated XynS20E will also be studied by using X-ray crystallography. In addition, the gene of xynS20E will be cloned and expressed in a high efficiency expression system. The application of the recombinant enzyme will also be estimated.瘤胃真菌乙醯聚木糖酯&#37238聚木糖&#37238X射線結晶分析法Rumen fungusacetylxylan esterasexylanaseX-ray crystallography