- 作者: 陳賢哲; 宋賢一; 蘇仲卿
- 作者服務機構: 國立臺灣大學農業化學系
- 中文摘要:
根據稻米穀實中二種可溶性ADPG合成活性與澱粉粒中澱粉合成活性間之相互飽和實驗結果,得以證明成熟期稻米
穀實中蔗糖與澱粉間轉變之生化路徑。即將一種具有蔗糖合成?及ADPG焦磷解?活性之可溶性酵素抽提液,以不同比
例與澱粉合成?混合,測定自蔗糖(+ADP)或G1P (+ATP)併入澱粉之醣?基量。結果發現蔗糖為比G1P較有效之醣
?基供給體,且在乳熟期穀實中含有較充足量蔗糖合成?以供合成澱粉所需前體醣核?酸。同時也發現,雖然UDP比ADP
更適於當做稻米蔗糖合成?之基質,但當與澱粉合成?進行聯鎖反應時只有ADPG之合成速率被加強,UDPG則無。從
上述結果可說明蔗糖合成?是乳熱期水稻穀實中自蔗糖合成澱粉系統之重要酵素。
由 - 英文摘要: The biochemical oathwav of sucrose-starch conversion in maturing rice grains was elucidated by titratinethe extractable ADPG* synthesizing activities witn the starch granule-associatea starch synthesizing activityand vice versa. For this purpose, a soluble enzyme preparation containing sucrose synthetase and ADPGpyrophosphorylase activities was combined with the starch synthetase preparation in various proportions. Theincorporation into starch of the glucosyl residue from either GIP (with ATP) or sucrose (with ADP) was thenmeasured. It was found that into starch sucrose was the better donor of the glucosyl unit than G1P. Ricegrains at milky, stage contained more sucrose synthetase than ADPG pyrophosphorylase which could syn-thesize the sugar nucleotide precursor for starch synthesis. It was also found that, although UDP was the bettersubstrate than ADP for rice sucrose synthetase, when coupled with starch synthetase, the synthetic rate of AD-PG, but not that of UDPG, was enhanced. From these results, it is suggested that sucrose synthetase plays asignificant role in sucrose-starch conversin in rice grains.
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