Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun 130024, China.
Department of Biochemistry, Molecular Biology and Biophysics, 6-155 Jackson Hall, University of Minnesota, 321 Church Street, Minneapolis, MN 55455, USA.
Int J Biol Macromol. 2021 Jun 30;181:793-800. doi: 10.1016/j.ijbiomac.2021.04.042. Epub 2021 Apr 15.
Here, we compare the content and composition of polysaccharides derived from the mycelium (40.4 kDa intracellular polysaccharide, IPS) and culture (27.2 kDa extracellular polysaccharide, EPS) of Penicillium oxalicum. Their chemical structures investigated by IR, NMR, enzymolysis and methylation analysis indicate that both IPS and EPS are galactomannans composed of α-1,2- mannopyranose (Manp) and α-1,6-Manp in a backbone ratio of ~3:1, respectively, both decorated with β-l,5-galactofuranose (Galf) side chains. A few β-l,6-Galf residues were also detected in the IPS fraction. EPS and IPS have different molecular weights (Mw) and degrees of branching. IPS obtained by alkaline extraction of P. oxalicum have been reported to be galactofuranans, a composition different from our IPS. Up to now, there have been no reports on the fine structure of EPS. Our results of galectin-mediated hemagglutination demonstrate that IPS exhibits greater inhibitory effects on five galectins compared with EPS. In addition, we find that Galf, a five-membered ring form of galactose, can also inhibit galectins. IPS may provide a new source of galectin inhibitors. These results increase our understanding of structure-activity relationships of polysaccharides as galectin inhibitors.
在这里，我们比较了草酸青霉菌丝体（40.4 kDa 胞内多糖，IPS）和培养物（27.2 kDa 胞外多糖，EPS）中多糖的含量和组成。通过红外光谱、核磁共振、酶解和甲基化分析研究它们的化学结构表明，IPS 和 EPS 均为半乳甘露聚糖，由α-1,2-甘露吡喃糖（Manp）和α-1,6-Manp 组成主链，比例约为 3:1，均由β-l,5-半乳糖呋喃糖（Galf）侧链修饰。在 IPS 部分也检测到少量的β-l,6-Galf 残基。EPS 和 IPS 的分子量（Mw）和支化度不同。通过碱性提取草酸青霉获得的 IPS 已被报道为半乳呋喃聚糖，与我们的 IPS 不同。到目前为止，还没有关于 EPS 精细结构的报道。我们用半乳凝集素介导的血凝试验的结果表明，与 EPS 相比，IPS 对五种半乳凝集素有更强的抑制作用。此外，我们发现半乳糖的五元环形式 Galf 也可以抑制半乳凝集素。IPS 可能为半乳凝集素抑制剂提供了新的来源。这些结果增加了我们对半乳糖凝集素抑制剂多糖结构-活性关系的理解。
