Thioredoxin-Linked Changes in Enzymes and Storage Proteins

这一建议是基于最近的证据，即NADP/硫氧还蛋白系统（由硫氧还蛋白h、NADP-硫氧还蛋白还原酶和NADPH组成）在种子萌发中起作用。硫氧还蛋白特异性地降低谷物的主要储存蛋白（小麦中的麦胶蛋白和谷蛋白），从而提高它们的溶解度和对蛋白酶的敏感性，并还原失活抑制淀粉降解酶-淀粉酶的二硫蛋白（大麦-淀粉酶/枯草菌素抑制剂）。该研究的延伸表明，硫氧还蛋白系统增强了面筋蛋白网络，从而提高了面包质量，并使胰蛋白酶抑制剂蛋白失活，从而有可能改善大豆的营养品质。涵盖这些发现的专利申请已经提交，硫氧还蛋白技术的商业化前开发已经开始。提出的研究解决了基本的新问题：(1)硫氧还蛋白在谷物（如小麦）的发芽中是否具有额外的调节功能？(2)硫氧还蛋白在萌发过程中氧化还原状态和丰度发生了哪些变化？(3)萌发过程中硫氧还蛋白还原所必需的酶活性是否发生变化？(4)硫氧还蛋白在大豆等其他类型种子的萌发中是否起作用？该研究将增加我们对硫氧还蛋白功能、酶调控和种子萌发的认识。这一建议源于我们的研究，我们已经提出了一种酶系统（“硫氧还蛋白系统”）的证据，它是已知最早的触发谷物（如小麦）发芽的信号。硫氧还蛋白系统的功能是：(1)激活籽粒的储存蛋白，从而使其成为幼苗的氮和能量来源；(2)激活淀粉降解所需的酶，从而提高萌发早期的能量生产。进一步研究表明，硫氧还蛋白体系具有一定的技术价值。该系统应用于面粉强化面筋，提高面包品质。硫氧还蛋白系统也中和动物消化酶的植物蛋白抑制剂。将硫氧还蛋白系统应用于大豆等食品，可提高其营养品质。涵盖这些用途的专利申请已经提交，硫氧还蛋白技术的商业化前开发已经开始。目前的项目代表了本研究基础方面的延伸。计划进行的实验将显示硫氧还蛋白系统在小麦中是否具有附加功能，以及该系统在其他种子类型的萌发中是否重要。＊＊＊

Buchanan 9316496 This proposal is based on recent evidence that the NADP/thioredoxin system (consisting of thioredoxin h, NADP-thioredoxin reductase and NADPH) functions in seed germination. Thioredoxin specifically reduces major storage proteins of cereals (gliadins and glutenins in wheat), thereby enhancing their solubility and susceptibility to proteinases, and reductively inactivates a disulfide protein that inhibits alpha-amylase, an enzyme of starch degradation (barley alpha-amylase/subtilisin inhibitor). An extension of this research has shown that the thioredoxin system strengthens the gluten protein network, thereby enhancing bread quality, and inactivates trypsin inhibitor proteins, thereby potentially improving the nutritional quality of soybean. A patent application covering these findings has been filed, and precommercial development of thioredoxin technology has commenced. The proposed research addresses fundamental new questions: (1) Does thioredoxin have additional regulatory functions in the germination of cereals such as wheat? (2) What changes in redox state and abundance does thioredoxin undergo during germination? (3) Does the activity of enzymes necessary for the reduction of thioredoxin change during germination? (4) Does thioredoxin function in the germination of other types of seeds such as soybean?. The research will add to our understanding of thioredoxin function, enzyme regulation and seed germination. %%% This proposal stems from research in which we have presented evidence for an enzyme system (the "thioredoxin system") that functions as the earliest known signal triggering the germination of cereals such as wheat. The thioredoxin system functions by (1) activating storage proteins of the grain, thereby enabling their use as a source of nitrogen and energy by the seedling, and (2) activating enzymes required for the degradation of starch, thereby enhancing energy production in the early phase of germination. An extension of this research indicates that the thioredoxin system is of technological value. Application of the system to flour strengthens gluten and enhances bread quality. The thioredoxin system also neutralizes plant protein inhibitors of animal digestive enzymes. Application of the thioredoxin system to foods like soybean may enhance their nutritional quality. A patent application covering these uses has been filed, and precommercial development of thioredoxin technology has commenced. The current project represents an extension of the fundamental aspects of this research. The experiments planned will show whether the thioredoxin system has additional functions in wheat and whether the system is important in the germination of other seed types. ***