ISIS Facility, STFC Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , U.K.
Dipartimento di Scienze , Università degli Studi "Roma Tre" , via della Vasca Navale 84 , 00146 Roma , Italy.
J Phys Chem B. 2018 Jul 26;122(29):7365-7374. doi: 10.1021/acs.jpcb.8b03450. Epub 2018 Jul 17.
Trehalose, commonly found in living organisms, is believed to help them survive severe environmental conditions, such as drought or extreme temperatures. With the aim of trying to understand these properties, two recent neutron scattering studies investigate the structure of trehalose water solutions but come to seemingly opposite conclusions. In the first study, which looks at two concentrations of trehalose-water mole ratios of 1:100 and 1:25, the conclusion is that trehalose hydrogen-bonds to water rather weakly and has a relatively minor impact on the structure of water in solution compared to bulk water. On the other hand, for the other, using a mole ratio of 1:38, the conclusion is that the water structure is rather substantially modified by the presence of trehalose and that the hydrogen bonding between water and trehalose hydroxyl groups is significant. In an attempt to try to understand the origin of these divergent views, which arise from similar but independent analyses of different neutron diffraction data, we have performed additional X-ray scattering experiments, which are highly sensitive to water structure, at the same trehalose-water concentrations used in the first study, and combined these with empirical potential structure refinement on the previously collected neutron data. The new analysis unequivocally confirms that trehalose does indeed have only a minor impact on the structure of water, at all three concentrations, and forms relatively weak hydrogen bonds with water. Far from being discrepant with the existing literature, our new analysis of the different datasets suggests a natural explanation for the increased glass-transition temperature of trehalose compared to other sugars and hence its enhanced effectiveness as a protectant against drought stress.
海藻糖广泛存在于生物体内，被认为有助于生物在干旱或极端温度等恶劣环境条件下生存。为了试图了解这些特性，最近有两项中子散射研究调查了海藻糖水溶液的结构，但得出了看似相反的结论。第一项研究观察了两种海藻糖-水摩尔比为 1:100 和 1:25 的浓度，得出的结论是海藻糖与水的氢键结合较弱，与体相水相比，对溶液中水的结构的影响相对较小。另一方面，对于另一种摩尔比为 1:38 的情况，结论是水的结构因海藻糖的存在而发生了相当大的改变，并且水和海藻糖羟基之间的氢键作用非常显著。为了试图理解这些源于对不同中子衍射数据进行类似但独立分析的分歧观点的起源，我们在与第一项研究相同的海藻糖-水浓度下进行了额外的 X 射线散射实验，这些实验对水结构高度敏感，并将其与之前收集的中子数据进行经验势结构细化相结合。新的分析明确证实，海藻糖确实只对所有三种浓度下水的结构产生轻微影响，并与水形成相对较弱的氢键。与现有文献完全一致的是，我们对不同数据集的新分析为海藻糖与其他糖相比玻璃化转变温度升高提供了自然的解释，因此它作为抗旱应激保护剂的效果增强。
