Oliver A E, Hincha D K, Crowe L M, Crowe J H
Section of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
Biochim Biophys Acta. 1998 Mar 6;1370(1):87-97. doi: 10.1016/s0005-2736(97)00246-0.
The glycosylated hydroquinone arbutin (4-hydroxyphenyl-beta-D-glucopyranoside) is abundant in certain resurrection plants, which can survive almost complete dehydration for prolonged periods. Little is known about the role of arbutin in vivo, but it is thought to contribute toward survival of the plants in the dry state. We have investigated the interactions of arbutin with model membranes under conditions of high and low hydration, as well as the possible participation of arbutin in carbohydrate glasses formed at low water contents. Retention of a trapped soluble marker inside large unilamellar vesicles and fusion of vesicles was monitored by fluorescence spectroscopy. Effects of arbutin on glass-transition temperatures and hydrated membrane phase-transition temperatures were measured by differential scanning calorimetry. The possible insertion of arbutin into membrane bilayers was estimated by following arbutin auto-fluorescence. Evidence is presented that arbutin does not change the glass-transition temperature of a sucrose/trehalose glass, but that arbutin does interact with hydrated membranes by insertion of the phenol moiety into the lipid bilayer. This interaction causes increased membrane leakage during air-drying by a mechanism other than vesicle-vesicle fusion. Implications of these effects on the dehydrated plant cells, as well as possible methods of obviating the damage, are discussed.
糖基化对苯二酚熊果苷（4-羟基苯基-β-D-吡喃葡萄糖苷）在某些复苏植物中含量丰富，这些植物能够在几乎完全脱水的状态下长时间存活。关于熊果苷在体内的作用知之甚少，但人们认为它有助于植物在干燥状态下存活。我们研究了熊果苷在高水合和低水合条件下与模型膜的相互作用，以及熊果苷在低含水量时形成的碳水化合物玻璃态中的可能参与情况。通过荧光光谱监测大单层囊泡内捕获的可溶性标记物的保留情况以及囊泡的融合情况。通过差示扫描量热法测量熊果苷对玻璃化转变温度和水合膜相变温度的影响。通过跟踪熊果苷自身荧光来估计熊果苷插入膜双层的可能性。有证据表明，熊果苷不会改变蔗糖/海藻糖玻璃的玻璃化转变温度，但熊果苷确实会通过酚基部分插入脂质双层与水合膜相互作用。这种相互作用通过囊泡-囊泡融合以外的机制导致风干过程中膜泄漏增加。讨论了这些效应对脱水植物细胞的影响以及避免损伤的可能方法。
