Ramirez John F, Kumara U G V S S, Arulsamy Navamoney, Boothby Thomas C
Department of Molecular Biology, University of Wyoming. Laramie, WY 82071.
Department of Chemistry, University of Wyoming. Laramie, WY 82071.
bioRxiv. 2023 Nov 16:2023.06.30.547256. doi: 10.1101/2023.06.30.547256.
Water is essential for metabolism and all life processes. Despite this, many organisms distributed across the kingdoms of life survive near-complete desiccation or anhydrobiosis (Greek for "life without water"). Increased intracellular viscosity, leading to the formation of a vitrified state is necessary, but not sufficient, for survival while dry. What properties of a vitrified system make it desiccation-tolerant or -sensitive are unknown. We have analyzed 18 different vitrified systems, composed of one of three protective disaccharides (trehalose, sucrose, or maltose) and varying amounts of glycerol, quantifying their enzyme-protective capacity and their material properties in a dry state. We find that protection conferred by mixtures containing maltose correlates strongly with increased water content, increased glass-transition temperature, and reduced glass former fragility, while the protection of glasses formed with sucrose correlates with increased glass transition temperature and the protection conferred by trehalose glasses correlates with reduced glass former fragility. Thus, different vitrified sugars confer protection through distinct material properties. Extending on this, we have examined the material properties of a dry desiccation tolerant and intolerant life stage from three different organisms. In all cases, the dried desiccation tolerant life stage of an organism had an increased glass transition temperature relative to its dried desiccation intolerant life stage, and this trend is also seen in all three organisms when considering reduced glass former fragility. These results suggest that while drying of different protective sugars results in vitrified systems with distinct material properties that correlate with their enzyme-protective capacity, in nature organismal desiccation tolerance relies on a combination of these properties. This study advances our understanding of how protective and non-protective glasses differ in terms of material properties that promote anhydrobiosis. This knowledge presents avenues to develop novel stabilization technologies for pharmaceuticals that currently rely on the cold-chain.
水对于新陈代谢和所有生命过程至关重要。尽管如此，分布在生命各王国的许多生物在近乎完全干燥或脱水生物状态（希腊语为“无水生命”）下仍能存活。细胞内粘度增加导致形成玻璃化状态是干燥时存活的必要条件，但并不充分。玻璃化系统的哪些特性使其具有耐干燥性或敏感性尚不清楚。我们分析了18种不同的玻璃化系统，这些系统由三种保护性二糖（海藻糖、蔗糖或麦芽糖）之一和不同量的甘油组成，量化了它们在干燥状态下的酶保护能力和材料特性。我们发现，含麦芽糖的混合物提供的保护与含水量增加、玻璃化转变温度升高以及玻璃形成剂脆性降低密切相关，而蔗糖形成的玻璃的保护与玻璃化转变温度升高相关，海藻糖玻璃提供的保护与玻璃形成剂脆性降低相关。因此，不同的玻璃化糖通过不同的材料特性提供保护。在此基础上，我们研究了来自三种不同生物的耐干燥和不耐干燥生命阶段的材料特性。在所有情况下，生物体干燥的耐干燥生命阶段相对于其干燥的不耐干燥生命阶段具有更高的玻璃化转变温度，并且在考虑玻璃形成剂脆性降低时，这一趋势在所有三种生物中也可见。这些结果表明，虽然不同保护性糖的干燥会导致具有与其酶保护能力相关的不同材料特性的玻璃化系统，但在自然界中，生物体的耐干燥性依赖于这些特性的组合。这项研究推进了我们对保护性和非保护性玻璃在促进脱水生物状态的材料特性方面如何不同的理解。这一知识为开发目前依赖冷链的药物新型稳定化技术提供了途径。
