Cellulosic microfibrils in plant cell walls are largely ensheathed and probably tethered by hydrogen-bonded hemicelluloses. Ensheathing may vary developmentally as hemicelluloses are peeled to enable cell expansion. We characterised a simple method to quantify ensheathed versus naked cellulosic surfaces based on the ability to adsorb a radiolabelled 'cellulose-complementary oligosaccharide', [3H]cellopentaitol. Filter-paper (cellulose) adsorbed 40% and >80% of aqueous 5 nM [3H]cellopentaitol within ∼1 and ∼20 h respectively. When [3H]cellopentaitol was rapidly dried onto filter-paper, ∼50% of it was desorbable by water, whereas after ∼1 day annealing in aqueous medium the adsorption became too strong to be reversible in water. 'Strongly' adsorbed [3H]cellopentaitol was, however, ∼98% desorbed by 6 M NaOH, ∼50% by 0.2 M cellobiose, and ∼30% by 8 M urea, indicating a role for hydrogen-bonding reinforced by complementarity of shape. Gradual adsorption was promoted by kosmotropes (1.4 M Na2SO4 or 30% methanol), and inhibited by chaotropes (8 M urea), supporting a role for hydrogen-bonding. [3H]Cellopentaitol adsorption was strongly competed by non-radioactive cello-oligosaccharides (Cell2-6), the IC50 (half-inhibitory concentration) being highly size-dependent: Cell2, ∼70 mM; Cell3, ∼7 mM; and Cell4-6, ∼0.05 mM. Malto-oligosaccharides (400 mM) had no effect, confirming the role of complementarity. The quantity of adsorbed [3H]cellopentaitol was proportional to mass of cellulose. Of seven cottons tested, wild-type Gossypium arboreum fibres were least capable of adsorbing [3H]cellopentaitol, indicating ensheathment of their microfibrillar surfaces, confirmed by their resistance to cellulase digestion, and potentially attributable to a high glucuronoarabinoxylan content. In conclusion, [3H]cellopentaitol adsorption is a simple, sensitive and quantitative way of titrating 'naked' cellulose surfaces.

中文翻译：

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使用纤维素互补低聚糖作为工具来探测棉纤维中暴露的纤维素表面和生长中的植物细胞壁。


植物细胞壁中的纤维素微原纤维大部分被包裹，可能被氢键半纤维素束缚。随着半纤维素的剥离以实现细胞扩增，鞘膜的发育可能会有所不同。我们描述了一种简单的方法，根据吸附放射性标记的“纤维素互补寡糖”、[3H] 纤维素戊醇的能力来量化鞘膜与裸纤维素表面。滤纸（纤维素）在 ∼1 和 ∼20 小时内分别吸附了 40% 和 >80% 的 5 nM [3H] 细胞戊醇水溶液。当 [3H] cellopentaitol 在滤纸上快速干燥时，其中约 50% 可被水解吸，而在水性介质中退火约 1 天后，吸附变得太强，无法在水中逆转。然而，“强”吸附的 [3H] 细胞戊醇被 6 M NaOH 解吸 ∼98%，被 0.2 M 纤维二糖解吸 ∼50%，被 8 M 尿素解吸 ∼30%，表明通过形状互补增强氢键的作用。kosmotropes （1.4 M Na2SO4 或 30% 甲醇） 促进逐渐吸附，并被离液剂 （8 M 尿素） 抑制，支持氢键的作用。[3 小时]细胞戊醇吸附与非放射性纤维寡糖 （Cell2-6） 强烈竞争，IC50 （半抑制浓度） 高度依赖于大小：Cell2，∼70 mM;Cell3，∼7 mM;和 Cell4-6，∼0.05 mM。麦芽低聚糖 （400 mM） 没有影响，证实了互补性的作用。吸附的 [3H] 细胞戊醇的量与纤维素的质量成正比。在测试的 7 种棉花中，野生型 Gossypium arboreum 纤维吸附 [3H] 细胞戊醇的能力最差，表明其微纤维表面被包裹，由它们对纤维素酶消化的抵抗性证实，并可能归因于高葡萄糖醛酸阿拉伯木聚糖含量。 总之，[3H] cellopentaitol 吸附是一种简单、灵敏和定量的“裸”纤维素表面滴定方法。