Department of Physics, Faculty of Science, Marmara University, Istanbul, 34722, Türkiye.
Eur Biophys J. 2024 Nov;53(7-8):405-414. doi: 10.1007/s00249-024-01720-0. Epub 2024 Sep 19.
Lignin, one of the most abundant biopolymers on Earth, is of great research interest due to its industrial applications including biofuel production and materials science. The structural composition of lignin plays an important role in shaping its properties and functionalities. Notably, lignin exhibits substantial compositional diversity, which varies not only between different plant species but even within the same plant. Currently, it is unclear to what extent this compositional diversity plays on the overall structure and dynamics of lignin. To address this question, this paper reports on the development of two models of lignin containing all guaiacyl (G) subunits with varied linkage sequences and makes use of all-atom molecular dynamics simulations to examine the impact of linkage sequence alone on the lignin's structure and dynamics. This work demonstrates that the structure of the lignin polymer depends on its linkage sequence at temperatures above and below the glass transition temperature ( ), but the polymers exhibit similar structural properties as it is approaching the viscous flow state (480 K). At low temperatures, both of lignin models have a local dynamics confined in a cage, but the size of cages varies depending on structural differences. Interestingly, at temperatures higher than , the different linkage sequence leads to the subtle dynamical difference which diminishes at 480 K.
木质素是地球上最丰富的生物聚合物之一，由于其在生物燃料生产和材料科学等领域的工业应用而备受关注。木质素的结构组成对其性质和功能起着重要作用。值得注意的是，木质素表现出显著的组成多样性，不仅在不同的植物物种之间存在差异，甚至在同一植物中也存在差异。目前，还不清楚这种组成多样性在多大程度上影响木质素的整体结构和动力学。为了解决这个问题，本文报道了两种含有不同连接序列的愈创木基（G）单元的木质素模型的开发，并利用全原子分子动力学模拟来单独研究连接序列对木质素结构和动力学的影响。这项工作表明，木质素聚合物的结构取决于其连接序列，无论是在玻璃化转变温度（Tg）以上还是以下的温度，但在接近粘性流动状态（480 K）时，聚合物表现出相似的结构性质。在低温下，两种木质素模型都具有局部动力学限制在笼中，但笼的大小取决于结构差异。有趣的是，在高于Tg 的温度下，不同的连接序列导致了细微的动力学差异，这种差异在 480 K 时消失。
