Exploring the molecular structure of starch granule during the initial stages of granule formation

由于淀粉这种自组装大分子的结构复杂性，它仍然是一个引起强烈科学兴趣的课题。在淀粉结构和结构的背景下，颗粒形成的起始仍不清楚。虽然从遗传学和生物化学的角度提出了理论，但迄今为止的研究并没有真正考虑到淀粉聚合物的物理和结构特征，以及它们在颗粒形成和早期颗粒发育中的作用。本文提出的研究旨在弥合这一差距；即，确定受不同生物合成酶影响的早期聚合物/颗粒的分子结构。我们的短期目标是确定淀粉颗粒发育早期阶段聚合物的分子结构，以可能解释颗粒形成的机制。我们建议在暂态淀粉和存储淀粉中测试这一前提。这是我们的假设，在颗粒发育的早期阶段的分子组织是保守的在瞬变和储存淀粉；这种结构很可能与颗粒形成密切相关。因此，本研究的目标是：1)表征瞬时淀粉颗粒的结构和形态特性，以及淀粉的直链淀粉和支链淀粉在不同光周期下的分子结构；2)研究发育中的玉米贮藏淀粉颗粒的结构和形态特征，以及直链淀粉和支链淀粉的分子结构。实现这两个目标的科学方法包括使用酶法结合色谱法来表征分子组分及其精细结构，x射线散射和量热法来研究半晶体部分的分子组织，显微镜来研究超分子结构的形态。该项目是新颖的，因为在瞬态或储存淀粉中开发淀粉聚合物的单元链组织以前从未被分析过。此外，这个项目的结果将有助于理解颗粒起始的可能机制；未知的知识。

Starch remains a subject of intense scientific interest because of the structural complexity of this self-assembling macromolecule. Within in the context of starch structure and architecture, the initiation of granule formation remains unclear. While theories have been proposed from genetics and biochemistry points of view, research to-date has not really taken into account the physical and structural features of starch polymers with respect to their role in granule initiation and early granule development. Research proposed herein, aims to bridge this gap; i.e., to determine the molecular architecture of the early polymers/granules as influenced by different biosynthetic enzymes. Our short-term goal is to determine the molecular architecture of polymers at early stages of starch granule development to likely explain the mechanism of granule initiation. We propose to test this premise in both transient and storage starches. It is our hypothesis that the molecular organization at early stages of granule development is conserved in both transient and storage starches; and that this structure is likely closely linked to the events of granule initiation. The objectives of this research, therefore, are to; 1) Characterize the structural and morphological properties of transient starch granules, and the molecular structure of amylose and amylopectin of starches at different photoperiods; and 2) Characterize the structural and morphological properties of granules, and the molecular structure of amylose and amylopectin of developing maize storage starches.The scientific approach for both objectives include the use of enzymatic methods combined with chromatography for characterization of molecular components and their fine structures, X-ray scattering and calorimetry to study the molecular organization in semi-crystalline parts, microscopy to study the morphology of supramolecular structures. The proposed project is novel because the unit chain organization of developing starch polymers in transient or storage starches has never been analyzed previously. Also, results from this project will contribute to an understanding of the likely mechanisms of granule initiation; knowledge that is as yet unknown.