POWRE: Novel Pectin Metabolizing Enzymes in Ripening Tomatoes

番茄果实成熟过程中的果胶代谢新酶研究本课题的重点是分离和鉴定番茄果实成熟过程中的两种果胶水解酶--鼠李糖半乳糖醛酸酶和果胶乙酰酯酶。研究者计划（1）随着果实开始成熟追踪这些酶活性的发展，和（2）开始纯化这些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广泛溶解之前，更知名的多聚半乳糖醛酸酶在成熟过程中产生。水果成熟时会发生许多生化变化。 在这项研究中，研究人员将研究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，发展风味和香气，并软化。 软化过程中的一个环节是果实细胞壁的破裂。 细胞壁由复杂的糖阵列组成，这些糖串在一起并相互交联，形成一个相当坚固的组件，保护细胞免受损害，并有助于维持植物组织的结构。 随着细胞壁的退化，被称为寡糖的小糖链被释放出来。 这些低聚糖中的一些可以进一步刺激成熟过程。 在这项研究中，研究者将试图纯化和表征一种或多种在成熟过程中参与细胞壁降解的酶。 特别是，她将研究一种酶，降解果胶，植物细胞壁的碳水化合物成分之一。 这种酶，即鼠李糖半乳糖醛酸酶，可以切断果胶中鼠李糖和半乳糖醛酸之间的键。 这种酶可以通过降解果胶分子来促进软化，并通过释放刺激性寡糖来调节成熟。 除了揭示与成熟相关的生物化学的重要方面外，该项目还与应用收获后生物学有关。 限制采收的水果的储存和运输的最重要的问题是过早软化。 该项目可以确定旨在操纵水果成熟的技术的重要目标。 这是一个权力项目;该奖项将使普罗迪博士获得必要的专业知识，以建立这一新的研究线在她的实验室。

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.