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脯氨酸作為一種理想的滲透調節物質有很多特性:脯氨酸的分子量小,是一種極易溶于水的氨基酸;在生理pH范圍內不帶靜電荷;能被細胞膜所保持;幾乎不引起酶解構的變化;生成迅速,并能高累積足以引起調節作用的量.這些特性使脯氨酸在植物抗逆境脅迫中有重要作用: 脯氨酸可以調節細胞的滲透勢:鹽脅迫情況下,植物細胞會因為細胞內水勢降低而容易失水.因此植物能否保持正常生長狀況,關鍵在于能否維持體內的水分平衡.脯氨酸作為一種可溶性較強的氨基酸,在正常的pH內不帶電荷.在滲透脅迫情況下,脯氨酸利用其較強的吸水能力來增強細胞的持水能力,同時脯氨酸和其他一些可溶性物質的累積可以降低細胞的水勢,進而驅使水分進入細胞或降低水分從細胞中流出,為細胞膨脹提供了膨壓. 脯氨酸可以穩定蛋白:
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.