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標題: 芋頭中澱粉合成脢性質與功能的探討
The Studies of Properties and Functions of Starch Synthases in Taro
作者: 蔣啟玲
關鍵字: 食品科技;應用研究;Starch granule;澱粉顆粒;澱粉合成?;芋頭;基因選殖;Starch synthase;Taro;Gene cloning
澱粉是植物體主要的儲藏性碳水化合物,高澱粉含量之作物,不僅作為人類的主食 ,更是許多加工食品及工業上的原料,而澱粉的理化性質,如糊化溫度、凝膠強度、老化狀況等,主要決定於其組成之直鏈及支鏈澱粉分子的含量與結構,許多化學方法應用於製造具特殊理化性質之修飾澱粉,而目前因生物技術之進展,使學者們著眼於瞭解澱粉生合成之機制,以期由自然界生產之。參與澱粉生合成的酵素有十數種,而與澱粉鏈長增加有關的為澱粉合成�,有澱粉粒結合性澱粉合成�及可溶性澱粉合成�兩類。芋屬天南星科植物,生長於熱帶及亞熱帶,其塊莖是熱帶地區人民主食之一,芋頭塊莖中長期貯藏性之澱粉顆粒,呈多角形大小僅1~5 mm,芋頭除鮮食外其澱粉顆粒具有加工應用性,本研究之目的在瞭解芋頭中澱粉合成�的性質及它們於催化澱粉結構形成上所扮演之角色。在此計畫中預計要完成以下的工作: 第一年:1.偵測芋頭中可溶性澱粉合成�之異構形數目。2.分離純化主要之可溶性澱粉合成。3.測定可溶性澱粉合成�之生化性質。4.製備可溶性澱粉合成�之抗體。 第二年:1.建立芋頭cDNA library。2.以DNA探針或抗體選殖可溶性澱粉合成�基因並加以定序。3.表現於適當之寄主細胞。4.以蛋白質工程技術瞭解酵素之活性部位。 第三年:1.於適當的作物或培養之組織中進行基因的破壞或回補作用。2.進行野生株、突變株及回補株所產生之澱粉結構及性質之分析。

Starch is the major storage carbohydrate of higher plants. Starchy crops not only is the energy supplier to human being, but also one of the important raw material for food and related industries. The physical acid chemical properties, such as the geletilitation temperature hardness of gel, retrogradation etc, of starches from various sources is related to the contents and structure of amylase and amylopection in the starch granule. Chemical-modified-starches were produced to fit the requirement of special application. Nowaday, the possibility of appling biotechnology in breeded crops producing starch with diverse physical acid chemical properties were attracted the attention of scientists. There are about 13 different enzymes involved in the biosynthetic pathways of starch. Granule bound starch synthase and soluble starch synthases catalyze elongation of a-1,4 glucosidic chain.Taro (Colocasia esculenta (L.) Scott) is a tropic tuber crop and is cultivated widely in many contries, including Taiwan. Taro starch had irregular, polygonal shapes and small granular size. Because of its small granular size, taro starch has been considered a good fillity agents for biodegradable polyethylene film and as a fat substitute.In order to elucidate the role of isoforms of starch synthases in the biosynthesis of taro starch, we are going to investigated the properties and function of starch synthases in taro.During the coming three years the folliing research works will be carried on: In the first year: 1.To determine isoforms of starch synthase in taro. 2.To isolate and purify the major soluble starch synthase in taro. 3.To analyze biochemical properties of the purified starch synthase. 4.To prepare antibodies against the starch synthase. In the second year: 1.To construct cDNA library of taro. 2.To clone starch synthase gene and to sequence the cloned gene. 3.To express the gene in proper host cells. 4.To deterimene the essentials amino acid residues in the active site by site-directed mutagenesis. In third year: 1.To construct an antisense vector containing starch synthase antisense cDNA and introduce into Agarobacterium tumefaciens. 2.To transform taro with A. tumefaciens carrying the antisense construct. 3.To isolate starch granules from transgenic plant and analyze the fine structure of starch granules.
其他識別: NSC89-2313-B005-057
Appears in Collections:食品暨應用生物科技學系

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