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首页> 外文期刊>Journal of Experimental Botany >Evidence for the absence of enzymatic reactions in the glassy state. A case study of xanthophyll cycle pigments in the desiccation-tolerant moss Syntrichia ruralis.
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Evidence for the absence of enzymatic reactions in the glassy state. A case study of xanthophyll cycle pigments in the desiccation-tolerant moss Syntrichia ruralis.

机译：在玻璃态下不存在酶促反应的证据。叶绿素循环色素在耐干燥苔藓Syntrichia Ruralis中的案例研究。

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Desiccation-tolerant plants are able to withstand dehydration and resume normal metabolic functions upon rehydration. These plants can be dehydrated until their cytoplasm enters a 'glassy state' in which molecular mobility is severely reduced. In desiccation-tolerant seeds, longevity can be enhanced by drying and lowering storage temperature. In these conditions, they still deteriorate slowly, but it is not known if deteriorative processes include enzyme activity. The storage stability of photosynthetic organisms is less studied, and no reports are available on the glassy state in photosynthetic tissues. Here, the desiccation-tolerant moss Syntrichia ruralis was dehydrated at either 75% or <5% relative humidity, resulting in slow (SD) or rapid desiccation (RD), respectively, and different residual water content of the desiccated tissues. The molecular mobility within dry mosses was assessed through dynamic mechanical thermal analysis, showing that at room temperature only rapidly desiccated samples entered the glassy state, whereas slowly desiccated samples were in a 'rubbery' state. Violaxanthin cycle activity, accumulation of plastoglobules, and reorganization of thylakoids were observed upon SD, but not upon RD. Violaxanthin cycle activity critically depends on the activity of violaxanthin de-epoxidase (VDE). Hence, it is proposed that enzymatic activity occurred in the rubbery state (after SD), and that in the glassy state (after RD) no VDE activity was possible. Furthermore, evidence is provided that zeaxanthin has some role in recovery apparently independent of its role in non-photochemical quenching of chlorophyll fluorescence.Registry Number/Name of Substance 0 (Plant Proteins). 0 (Xanthophylls). 059QF0KO0R (Water). 51C926029A (violaxanthin). EC 1 (Oxidoreductases). EC 1 (violaxanthin de-epoxidase).
机译：耐干燥植物能够承受脱水并在补充水分后恢复正常的代谢功能。这些植物可以脱水，直到它们的细胞质进入“玻璃态”，其中分子的迁移率大大降低。在耐干燥种子中，可以通过干燥和降低贮藏温度来延长其寿命。在这些条件下，它们仍然缓慢变质，但是不知道退化过程是否包括酶活性。对光合生物的储存稳定性的研究较少，并且没有关于光合组织中玻璃态的报道。在这里，耐干燥苔藓Syntrichia Ruralis在75％或<5％相对湿度下脱水，分别导致缓慢（SD）或快速干燥（RD），以及干燥组织的不同残留水分。通过动态机械热分析评估了干苔藓中的分子迁移率，结果表明，在室温下，仅快速干燥的样品进入玻璃态，而缓慢干燥的样品则处于“橡胶”状态。 SD观察到紫黄质循环活性，质体小球积聚和类囊体重组，但RD观察不到。紫黄质循环活性主要取决于紫黄质脱环氧酶（VDE）的活性。因此，提出酶活性在橡胶态（SD之后）发生，而在玻璃态（RD之后）没有VDE活性是可能的。此外，提供了证据表明玉米黄质在恢复中具有一定作用，显然与其在叶绿素荧光的非光化学猝灭中的作用无关。登记号/物质0（植物蛋白）的名称。 0（叶黄素）。 059QF0KO0R（水）。 51C926029A（紫黄质）。 EC 1（氧化还原酶）。 EC 1（紫黄质脱环氧化物酶）。

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