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The physical state of osmoregulatory solutes in unicellular algae. A natural-abundance carbon-13 nuclear-magnetic-resonance relaxation study

机译:单细胞藻体中渗透调节溶质的物理状态。自然丰度的碳13核磁共振弛豫研究

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pNatural-abundance 13C n.m.r. spin-lattice relaxation-time measurements have been carried out on intact cells of the unicellular blue-green alga Synechococcus sp. and the unicellular green alga Dunaliella salina, with the aim of characterizing the environments of the organic osmoregulatory solutes in these salt-tolerant organisms. In Synechococcus sp., all of the major organic osmoregulatory solute, 2-O-alpha-D-glucopyranosylglycerol, is visible in spectra of intact cells. Its rotational motion in the cell is slower by a factor of approx. 2.4 than in aqueous solution, but the molecule is still freely mobile and therefore able to contribute to the osmotic balance. In D. salina, only about 60% of the osmoregulatory solute glycerol is visible in spectra of intact cells. The rotational mobility of this observable fraction is approximately half that found in aqueous solution, but the data also indicate that there is a significant concentration of some paramagnetic species in D. salina which contributes to the overall spin-lattice relaxation of the glycerol carbon atoms. The non-observable fraction, which must correspond to glycerol molecules that have very broad 13C resonances and that are in slow exchange with bulk glycerol, has not been properly characterized as yet, but may represent glycerol in the chloroplast. The implications of these findings in relation to the physical state of the cytoplasm and the mechanism of osmoregulation in these cells are discussed./p
机译:>自然丰度13C n.m.r.在单细胞蓝绿藻Synechococcus sp。的完整细胞上进行了自旋晶格弛豫时间测量。以及单细胞绿藻杜氏盐藻(Dunaliella salina),目的是表征这些耐盐生物中有机渗透调节溶质的环境。在Synechococcus sp。中,完整细胞的光谱中可见所有主要的有机渗透调节溶质2-O-α-D-吡喃葡萄糖基甘油。它在单元中的旋转运动要慢大约两倍。 2.4比水溶液中的多,但该分子仍可自由移动,因此能够促进渗透平衡。在盐藻中,在完整细胞的光谱中仅可见约60%的渗透调节溶质甘油。该可观察级分的旋转迁移率约为水溶液中的旋转迁移率的一半,但数据还表明盐沼中存在一些浓度较高的顺磁性物质,这有助于甘油碳原子的整体自旋晶格弛豫。不可观察的馏分必须对应于具有13C共振非常宽泛且与大量甘油缓慢交换的甘油分子,目前尚未得到适当表征,但可能代表叶绿体中的甘油。讨论了这些发现与这些细胞质的物理状态以及渗透调节机制有关的意义。

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