美国路易斯安那州立大学Tuo Wang团队通过固态核磁共振鉴定和定量了微藻多糖结构。相关研究成果发表在2021年11月4日出版的《美国化学会杂志》。

微藻是自然界广泛分布的光合生物，是一种可持续的生物产品来源。其碳水化合物组分也是生物能源生产和生物修复的有希望的候选物，但细胞中多相聚合物的结构表征仍然是一个棘手的问题。

该文中，研究人员提出了一个广泛适用的协议，用于使用魔角旋转（MAS）固态NMR（ssNMR）光谱鉴定和定量聚糖含量，并通过糖基连接和质谱（MS）推断的成分分析进行验证。一个均匀¹³C标记的绿色微藻贝氏副小球藻的二维¹³C–¹³C相关ssNMR谱表明，淀粉是天然纤维素缺乏菌株中含量最丰富的多糖，并且该聚合物在细胞中具有组织良好且高度刚性的结构。一些木糖存在于细胞壁的活动域和刚性域中，其化学位移部分与植物中鉴定的扁平带状2倍木聚糖对齐。

令人惊讶的是，大多数其他碳水化合物无论在糖脂或细胞壁中的分布如何，在很大程度上是可移动的。该结构见解与这种纤维素缺乏菌株的高消化率相关，细胞内ssNMR方法将有助于研究其他经济上重要藻类物种的研究。

附：英文原文

Title: Identification and Quantification of Glycans in Whole Cells: Architecture of Microalgal Polysaccharides Described by Solid-State Nuclear Magnetic Resonance

Author: Alexandre Poulhazan, Malitha C. Dickwella Widanage, Artur Muszyński, Alexandre A. Arnold, Dror E. Warschawski, Parastoo Azadi, Isabelle Marcotte, Tuo Wang

Issue&Volume: November 4, 2021

Abstract: Microalgae are photosynthetic organisms widely distributed in nature and serve as a sustainable source of bioproducts. Their carbohydrate components are also promising candidates for bioenergy production and bioremediation, but the structural characterization of these heterogeneous polymers in cells remains a formidable problem. Here we present a widely applicable protocol for identifying and quantifying the glycan content using magic-angle-spinning (MAS) solid-state NMR (ssNMR) spectroscopy, with validation from glycosyl linkage and composition analysis deduced from mass-spectrometry (MS). Two-dimensional 13C–13C correlation ssNMR spectra of a uniformly 13C-labeled green microalga Parachlorella beijerinckii reveal that starch is the most abundant polysaccharide in a naturally cellulose-deficient strain, and this polymer adopts a well-organized and highly rigid structure in the cell. Some xyloses are present in both the mobile and rigid domains of the cell wall, with their chemical shifts partially aligned with the flat-ribbon 2-fold xylan identified in plants. Surprisingly, most other carbohydrates are largely mobile, regardless of their distribution in glycolipids or cell walls. These structural insights correlate with the high digestibility of this cellulose-deficient strain, and the in-cell ssNMR methods will facilitate the investigations of other economically important algae species.

DOI: 10.1021/jacs.1c07429

Source: https://pubs.acs.org/doi/10.1021/jacs.1c07429