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  • 脯氨酸的作用机制
  • 本站编辑:浙江省富阳东辰生物工程有限公司发布日期:2019-06-13 16:27 浏览次数:

1.脯氨酸(Proline)在植物中的分布 植物体内游离的脯氨酸主要分布在光和器官和生殖器官.在其他组织和器官中,脯氨酸的量相对较少.陈托兄在研究不同类型抗盐植物水平游离脯氨酸的分配时,对三种类型的植物进行了分析:稀盐植物,泌盐植物,拒盐植物.稀盐植物中游离脯氨酸的含量很低,拒盐植物游离脯氨酸的量较高,泌盐植物游离脯氨酸的量介于二者之间.不过他们有一个共同的特征:游离脯氨酸多集中的代谢旺盛的器官和生殖器官,这是因为植物在受到胁迫时会优先保护这些器官.这也是植物在长期进化过程中自然选择的结果.</p>

2.脯氨酸(Proline)在盐胁迫下累积的生物学意义 植物在盐胁迫情况下一般会采取两种方式来累积脯氨酸:一种是当植物遇到渗透胁迫时,高盐的胁迫信号通过各级信号途径传递,使得与渗透调节物质相关的基因表达(如脯氨酸合成酶基因),导致胁迫诱导的基因产物(累积),从而维持细胞内水分平衡.一种方式就是将液泡中储存的脯氨酸运输到胞质中使细胞中脯氨酸急剧增加来抵抗高盐环境.

脯氨酸作为一种理想的渗透调节物质有很多特性:脯氨酸的分子量小,是一种极易溶于水的氨基酸;在生理pH范围内不带静电荷;能被细胞膜所保持;几乎不引起酶解构的变化;生成迅速,并能高累积足以引起调节作用的量.这些特性使脯氨酸在植物抗逆境胁迫中有重要作用: 脯氨酸可以调节细胞的渗透势:盐胁迫情况下,植物细胞会因为细胞内水势降低而容易失水.因此植物能否保持正常生长状况,关键在于能否维持体内的水分平衡.脯氨酸作为一种可溶性较强的氨基酸,在正常的pH内不带电荷.在渗透胁迫情况下,脯氨酸利用其较强的吸水能力来增强细胞的持水能力,同时脯氨酸和其他一些可溶性物质的累积可以降低细胞的水势,进而驱使水分进入细胞或降低水分从细胞中流出,为细胞膨胀提供了膨压. 脯氨酸可以稳定蛋白:

脯氨酸在植物体内不带电荷,又具有偶极性,它不会插入到蛋白质分子疏水相中引起蛋白质变性.在渗透胁迫情况下,它可以和酶相互作用从而保护蛋白的结构和功能,维持酶的活力.脯氨酸还可以改善细胞膜的水环境,增强膜结构的稳定. 脯氨酸可以作为氮素和碳架,在胁迫解除后为植物提供能源,有助于植物恢复正常生长.此外,脯氨酸在植物受害的过程中,可能作为氨的解毒剂.脯氨酸代谢的过程中产生NADP+(NADP+是戊糖磷酸合成NADPH的必要成分),使NADP+/NADPH比例升高.从这一点可以看出,在盐胁迫下,脯氨酸累积可以为植物细胞的光合作用和呼吸作用的氧化还原提供NAD和NADP.

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1. Distribution of Proline in plants Free proline in plants are mainly distributed in light and organs and reproductive organs. In other tissues and organs, the quantity of proline are relatively few. Chen's brother in the study of different types of salt resistance of plant level when the distribution of free proline, analyses the three types of plants: dilute salt plant, secrete salt plant, from salt plant. Dilute salt content of free proline in plants is very low, from high salt plant the amount of free proline, secrete salt plant the amount of free proline between the two. But they have one common feature: the metabolism of free proline concentration more exuberant organs and reproductive organs, this is because the plants priority protection when under stress These organs. This is also the result of natural selection over a long period of time. / p>

2. Proline (Proline accumulation under salt stress the biological significance of plants under salt stress condition generally adopt two ways to accumulation of Proline: one kind is when plants meet with osmotic stress, high salt stress signals through various ways, making gene expression related to osmotic regulation substances (such as Proline synthase gene), causes the stress induced gene product (cumulative), so as to maintain water balance in the cell. A way will be stored in the vacuole Proline transport to the dramatic rise in the cytoplasm of the cell Proline to resist high salt environment.

As an ideal osmotic regulator, proline has many characteristics: the molecular weight of proline is small, and it is an amino acid easily soluble in water; No static charge in the physiological pH range; Can be retained by cell membranes; Almost no change in enzyme deconstruction; These characteristics make proline play an important role in plant resistance to stress and stress: Proline can regulate cell osmotic potential: salt stress conditions, plant cells is replaced because of the reduced water in cells. So the plants can maintain normal growth, the key lies in whether to maintain water balance in the body. As a kind of soluble proline stronger amino acids, with no charge within the normal pH. In the case of osmotic stress, proline is using its strong ability of absorbing water to enhance cell water-holding capacity, at the same time, the accumulation of proline and other soluble substances can reduce cell water potential, thus driving water into cells and reduce the water outflow from the cells, provides the cell expansion turgor pressure. Proline can stabilize protein:

Proline in plants in vivo without charge, have dipolar again, it won't be inserted into the hydrophobic phase caused by protein denaturation of protein molecules. In the case of osmotic stress, it can and interaction in order to ensure the structure and function of the protein enzymes, to maintain the vitality of enzyme. Proline can also improve the water environment of the cell membrane, increase the stability of the membrane structure. Proline could be used as nitrogen and carbon frame, provides the energy for plants, after stress relieve helps plants returned to normal growth. In addition, in the process of proline in plants suffer, probably as ammonia antidote. Proline metabolism in the process of producing NADP (NADP It can be seen from this that under salt stress, proline accumulation can provide NAD and NADP for the REDOX of photosynthesis and respiration of plant cells.