Nothnagel E A, McNeil M, Albersheim P, Dell A
Department of Chemistry, University of Colorado, Boulder, Colorado 80309.
Plant Physiol. 1983 Apr;71(4):916-26. doi: 10.1104/pp.71.4.916.
Elicitors of phytoalexin accumulation in soybean (Glycine max L. Merr., cv Wayne) cotyledons were released from soybean cell walls and from citrus pectin by partial acid hydrolysis. These two hydrolysates yielded nearly identical distributions of elicitor activity when fractionated on anion-exchange columns. Chromatography of the pectin elicitor on gel filtration and high-pressure anion-exchange columns did not further purify the elicitor. Elicitor activity of the preparation was lost by treatment with either endo-alpha-1,4-polygalacturonase or pectate lyase. Glycosyl residue compositions of the purified elicitors from cell walls and pectin were both found to be approximately 98% galacturonosyl residues. Linkage analysis of the pectin elicitor showed that most, if not all, of the galacturonosyl residues were alpha-1,4-linked. The high-mass molecular ions detected by fast atom bombardment-mass spectrometry of the most active elicitor fractions from cell walls and pectin both corresponded precisely to a molecule composed of 12 galacturonosyl residues. These results suggest that dodeca-alpha-1,4-d-galacturonide is the active elicitor, but the possibility remains that the active component could be a slightly modified oligogalacturonide present, but not detected, in the purified fractions.
通过部分酸水解从大豆细胞壁和柑橘果胶中释放出了能诱导大豆（Glycine max L. Merr.，品种Wayne）子叶中植保素积累的激发子。当在阴离子交换柱上进行分级分离时，这两种水解产物产生了几乎相同的激发子活性分布。果胶激发子在凝胶过滤柱和高压阴离子交换柱上的色谱分析并没有进一步纯化该激发子。用内切α-1,4-聚半乳糖醛酸酶或果胶酸裂解酶处理该制剂会使其激发子活性丧失。从细胞壁和果胶中纯化得到的激发子的糖基残基组成均被发现约98%为半乳糖醛酸残基。对果胶激发子的连接分析表明，大部分（如果不是全部的话）半乳糖醛酸残基是α-1,4-连接的。通过快速原子轰击质谱法检测到的来自细胞壁和果胶的最具活性的激发子组分的高质量分子离子都精确地对应于一个由12个半乳糖醛酸残基组成的分子。这些结果表明十二聚-α-1,4-D-半乳糖醛酸是活性激发子，但仍有可能活性成分是纯化组分中存在但未检测到的稍有修饰的寡聚半乳糖醛酸。
