Waldron K W, Selvendran R R
AFRC Institute of Food Research, Norwich Research Park, Colney, U.K.
Phytochemistry. 1992 Jun;31(6):1931-40. doi: 10.1016/0031-9422(92)80336-d.
Cell wall material (CWM) was prepared from sections of fresh and aerobically-stored asparagus (Asparagus officinalis, L. cv. Connovor Collossus) stems. Polymers were solubilized from the CWM by successive extraction with cyclohexane-trans-1,2-diamine-N N N' N'-tetraacetate (CDTA), Na2CO3 and KOH to leave the alpha-cellulose residue which contained a significant amount of cross-linked pectic polysaccharides. The polymers were fractionated by anion-exchange chromatography and selected fractions were subjected to methylation analysis. The storage-related decrease in (1-4)-linked Galp was detected in all the fractions rich in pectic polysaccharides, particularly in the CDTA, Na2CO3, 0.5 M KOH fractions and alpha-cellulose residue. A smaller decrease in Araf was also observed. This was mainly due to a decrease in (1-5)-linked Araf in the Na2CO3-1-soluble polymers, and terminal Araf in the alpha-cellulose residue. There was evidence for the occurrence of significant amounts of complexes containing pectic polysaccharides and xylans having a relatively low degree of polymerization in the dilute alkali-soluble polymers, and some of these contained phenolic compounds; the storage-induced increase in (1-4)-linked Xylp was confined to these polymers. Interestingly, no free acidic xylans could be detected in the 1 M and 4 M KOH-soluble polymers; instead, the bulk of the hemicellulosic polysaccharides appeared to be mixtures of xyloglucans and xylans in which the ratio of xyloglucan to xylan increased with increasing strength of alkali used for extraction of the polymers. The non-degradative extraction and fractionation procedures revealed heterogeneity in pectic polysaccharides, pectic polysaccharide-xylan complexes and xyloglucans in close association with xylans. The possible relationship between pectic polysaccharide-xylan-phenolic complexes and the onset of lignification in maturing tissues is discussed.
细胞壁物质（CWM）取自新鲜的、经需氧储存的芦笋（石刁柏，品种为Connovor Collossus）茎段。通过用环己烷 - 反式 - 1,2 - 二胺 - N,N,N',N'-四乙酸（CDTA）、碳酸钠和氢氧化钾连续萃取，从CWM中溶解聚合物，留下含有大量交联果胶多糖的α-纤维素残渣。聚合物通过阴离子交换色谱法分级分离，选定的级分进行甲基化分析。在所有富含果胶多糖的级分中，特别是在CDTA、碳酸钠、0.5M氢氧化钾级分和α-纤维素残渣中，检测到与（1→4）连接型半乳糖（Galp）相关的储存相关减少。阿拉伯糖（Araf）也有较小程度的减少。这主要是由于碳酸钠 - 1可溶聚合物中（1→5）连接型Araf以及α-纤维素残渣中末端Araf的减少。有证据表明，在稀碱可溶聚合物中存在大量含有果胶多糖和聚合度相对较低的木聚糖的复合物，其中一些含有酚类化合物；储存诱导的（1→4）连接型木糖（Xylp）增加仅限于这些聚合物。有趣的是，在1M和4M氢氧化钾可溶聚合物中未检测到游离酸性木聚糖；相反，大部分半纤维素多糖似乎是木葡聚糖和木聚糖的混合物，其中木葡聚糖与木聚糖的比例随着用于萃取聚合物的碱强度增加而增加。非降解性萃取和分级分离程序揭示了果胶多糖、果胶多糖 - 木聚糖复合物和与木聚糖紧密相关的木葡聚糖中的异质性。讨论了果胶多糖 - 木聚糖 - 酚类复合物与成熟组织中木质化开始之间的可能关系。
