Structures and properties of arnylopectin and phytoglycogen in the endosperm of sugary-1 mutants of rice
Structures and properties of arnylopectin and phytoglycogen in the endosperm of sugary-1 mutants of rice
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DOI：
10.1006/jcrs.2002.0485
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发表时间：
2003-03-01
影响因子：
3.8
通讯作者：
Nakamura, Y
中科院分区：
文献类型：
--
作者：
Wong, KS;Kubo, A;Nakamura, Y
淀粉去分支酶(DBE)缺乏，糖-1突变导致了更高分枝的α-葡聚糖的生物合成，以植物糖原和含糖支链淀粉的形式存在，而不是野生型支链淀粉。植物糖原和含糖支链淀粉分别位于水稻胚乳的内层和外层。对这些来自不同糖型严重程度的等位基因突变体的葡聚糖的详细分析表明，与野生型支链淀粉相比，含糖支链淀粉由更多的DP<；12短链组成，而DP13-24链更少，并且这种变化反映在较低的相对分子质量、较小的旋转半径和更密集的分子上。这些变化导致了与野生型相比，起始糊化温度降低，峰值粘度降低，结晶度降低，糖类淀粉颗粒表面粗糙，颗粒细小，破裂。这些结果表明，DBE损伤引起的支链淀粉精细结构的改变对淀粉的形态和理化性质有很大的影响。糖-1突变株的植物糖原是由多个组分组成的，它们的相对分子质量和旋转半径都比糖基支链淀粉和支链淀粉小。高度支化的植物糖原是比含糖支链淀粉和支链淀粉更紧密的分子，表现出更大的分散密度。这些结果表明，水稻胚乳中DBE的水平控制着支链α-葡聚糖的生物合成途径，并产生支链淀粉、含糖支链淀粉和植物糖原。(C)2002爱思唯尔科学有限公司。保留所有权利。
Starch debranching enzyme (DBE)-deficient, sugary-1 mutations of rice caused the biosynthesis of more highly branched alpha-glucan in the form of phytoglycogen and sugary-amylopectin rather than wild-type amylopectin. Phytoglycogen and sugary-amylopectin are located in the inner and outer regions of the rice endosperm, respectively. Detailed analyses of these glucans from a variety of allelic mutants with different severity of sugary phenotype revealed that sugary-amylopectins consisted of more short chains of DP < 12 but fewer chains of DP13-24 than did wild-type amylopectin, and the alterations reflected on lower molecular weights, smaller gyration radii, and denser molecules. These changes resulted in lower onset gelatinization temperature, lower peak viscosity, lesser degree of crystallinity, and smaller and cracked granules with rough surface of sugary starch granules as compared with that of the wild-type. These results indicate that changes in the fine structure of amylopectin induced by lesion of DBE greatly influence the morphological and physicochemical properties of starch.Phytoglycogens from sugary-1 mutants were composed of multiple components of smaller molecular weights and gyration radii than sugary-amylopectin and amylopectin. The highly branched phytoglycogens were more tightly packed molecules exhibiting greater dispersed densities than sugary-amylopectin and amylopectin. These results suggest that the levels of DBE in rice endosperm control the biosynthetic pathway of branched alpha-glucans and produce amylopectin, sugary-amylopectin and phytoglycogen. (C) 2002 Elsevier Science Ltd. All rights reserved.