Rhamnogalacturonan I (RG-I), a polysaccharide found in different types of plant cell walls, fulfills specific functions, the structural basis of which remains unclear. Generalized 2D correlation FTIR spectroscopy with dehydration was employed to reveal the structure and interactions in flax RG-I solution and microwave treated gel. Varying water content allowed emphasizing a role of solvent in maintaining different structures. In the gel, 2D correlation maps prove the existence of a conformationally uniform highly hydrated structure. Such a structure is supposed to correspond to non-associated galactan helices stabilized by rare junctions. In colloidal solution the side chains of RG-I associate heterogeneously due to constrains imposed by stiff backbone. Galactan-enriched fraction of RG-I with enzymatically cleaved backbone revealed the tendency of galactan chains to strongly associate in solution. The obtained results shed light on the possible role of backbone and side chains in RG-I spatial organization and confirm the sensitivity and potential of 2D correlation FTIR spectroscopy to probe local ordered structures in non-crystalline polysaccharides.

Rhamnogalacturonan I（RG-1）是一种在不同类型的植物细胞壁中发现的多糖，具有特定的功能，其结构基础尚不清楚。带有脱水的广义二维相关FTIR光谱被用来揭示亚麻RG-1溶液和微波处理过的凝胶的结构和相互作用。不同的水含量可以强调溶剂在维持不同结构中的作用。在凝胶中，二维相关图证明存在构象均匀的高度水合结构。假定这种结构对应于通过稀少的连接点稳定的非缔合的半乳聚糖螺旋。在胶体溶液中，由于刚性骨架施加的约束，RG-1的侧链异质结合。富含半乳聚糖的RG-1馏分具有酶促裂解的骨架，揭示了半乳聚糖链在溶液中强烈缔合的趋势。获得的结果揭示了骨架和侧链在RG-I空间组织中的可能作用，并证实了二维相关FTIR光谱法探测非晶多糖中局部有序结构的敏感性和潜力。