POWRE: Novel Pectin Metabolizing Enzymes in Ripening Tomatoes

番茄成熟果实中果胶代谢的新酶Proposal：0075074 Gerry Prody，pi本项目的重点是分离和鉴定成熟番茄果实中的两种果胶水解酶--鼠李半乳糖醛酸酶和果胶乙酰酯酶。研究人员计划(1)跟踪这些酶活性在果实开始成熟时的发展情况，以及(2)开始提纯这两种蛋白质中的一种或两种。如果成功，这项工作将有助于解释为什么水果细胞壁果胶在成熟过程中更知名的聚半乳糖醛酸酶产生之前被广泛溶解。当水果成熟时，会发生许多生化变化。在这项研究中，研究人员将观察番茄果实成熟过程中的一个或多个生化事件。随着成熟的发生，水果变红，产生味道和香气，并变软。这种软化过程中的一个事件是水果细胞壁的破裂。细胞壁由复杂的糖阵列组成，这些糖相互串连并相互交叉，形成一个相当坚硬的组件，保护细胞免受损害，并帮助维持植物组织的结构。随着细胞壁的恶化，称为低聚糖的小糖链被释放出来。其中一些寡糖可能会进一步刺激成熟过程。在这项研究中，研究人员将试图纯化和鉴定与成熟过程中细胞壁降解有关的一种或多种酶。特别是，她将研究一种降解果胶的酶，果胶是植物细胞壁的碳水化合物成分之一。这种酶，鼠李糖半乳糖醛酸酶，在果胶中的糖鼠李糖和半乳糖醛酸之间裂解键。这种酶可以通过降解果胶分子来促进软化，并通过释放刺激性低聚糖来调节成熟。除了揭示与成熟相关的生物化学的重要方面外，该项目还与应用后收获生物学相关。限制果实储存和运输的最重要问题是果实过早软化。该项目可能确定旨在控制水果成熟的技术的重要目标。这是一个POWRE项目；该奖项将使Prody博士能够获得在她的实验室建立这一新研究路线所需的专业知识。

ABSTRACTNovel Pectin Metabolizing Enzymes in Ripening Tomato FruitProposal: 0075074Gerry Prody, PIThe focus of this project is the isolation and characterization two pectin hydrolyzing enzymes, rhamnogalacturonase and pectin acetylesterase, in ripening tomato fruits. The investigator plans to (1) trace the development of these enzyme activities as fruits begin to ripen and (2) begin purification of one or both of these proteins. If successful, this work will help to explain why fruit cell wall pectins are extensively solubilized before the more well-known polygalacturonase enzymes are produced during ripening. Many biochemical changes occur as a fruit ripens. In this study, the investigator will look at one or more of these biochemical events during ripening of tomato fruit. As ripening occurs, the fruit turns red, develops flavor and aroma, and softens. One of the events involved in this softening is the breakdown of the cell walls in the fruit. Cell walls consist of complex arrays of sugars strung together and cross-linked to one another to make a fairly rigid assembly that protects the cell from damage and helps maintain the structure of plant tissues. As cell walls deteriorate, small chains of sugars, called oligosaccharides, are released. Some of these oligosaccharides may further stimulate the ripening process. In this study, the investigator will attempt to purify and characterize one or more of the enzymes involved in cell wall degradation during ripening. In particular, she will study an enzyme that degrades pectin, one of the carbohydrate components of plant cell walls. The enzyme, rhamnogalacturonase, cleaves bonds between the sugars rhamnose and galacturonic acid in pectin. This enzyme can serve to promote softening by degrading the pectin molecules and to regulate ripening by releasing stimulatory oligosaccharides. In addition to revealing important aspects of ripening-related biochemistry, this project has relevance to applied post-harvest biology. The most important problem that limits storage and transport of harvested fruits is premature softening. This project may identify important targets for technologies aimed at manipulation of fruit ripening. This is a POWRE project; the award will enable Dr.Prody to acquire the expertise necessary to establish this new line of research in her laboratory.