Institute of Physiology, Komi Science Centre, The Urals Branch of the Russian Academy of Sciences, 167982 Syktyvkar, Russia.
Carbohydr Res. 2009 Dec 14;344(18):2602-5. doi: 10.1016/j.carres.2009.08.031. Epub 2009 Aug 28.
The callus culture of duckweed cultivated on medium containing different concentrations of beta-galactosidase was shown to produce the following polysaccharides: pectin lemnan LMC, intracellular AG1, and extracellular AG2 arabinogalactans. The samples of lemnan with 46% galactose residue reduction and 9-46% increased galacturonic acid residue content were obtained at beta-galactosidase concentrations of 10(-3)-10(-1)mg/mL. The most substantial alterations in the sugar composition of pectin were found to occur in the fraction with a molecular mass of 100-300 kDa. Low concentrations of enzyme failed to influence the sugar composition of intracellular arabinogalactan, whereas high concentrations were shown to decrease the amount of arabinose residues in AG1 and to cause galactan formation. Extracellular galactan was found to be produced on the medium with 10(-1) and 1mg/mL beta-galactosidase whereas extracellular arabinogalactan AG2 was shown to be biosynthesized without beta-galactosidase or at a beta-galactosidase concentration of 10(-3)mg/mL. Alterations in the sugar composition of polysaccharides were shown to be connected with the increasing activity of alpha-l-arabinofuranosidase and beta-galactosidase, and with the decreasing activity of intracellular polygalacturonase.
浮萍的愈伤组织在含有不同浓度β-半乳糖苷酶的培养基中培养，被证明能产生以下多糖：果胶 lemnan LMC、细胞内 AG1 和细胞外 AG2 阿拉伯半乳聚糖。在 10(-3)-10(-1)mg/mL 的β-半乳糖苷酶浓度下，获得了具有 46%半乳糖残基减少和 9-46%增加半乳糖醛酸残基含量的 lemnan 样品。发现果胶的糖组成发生了最大的变化，发生在分子量为 100-300 kDa 的部分。低浓度的酶未能影响细胞内阿拉伯半乳聚糖的糖组成，而高浓度的酶则降低了 AG1 中的阿拉伯糖残基的含量，并导致半乳糖聚糖的形成。在 10(-1)和 1mg/mL β-半乳糖苷酶的培养基中发现了细胞外半乳聚糖的产生，而在没有β-半乳糖苷酶或β-半乳糖苷酶浓度为 10(-3)mg/mL 的情况下，细胞外阿拉伯半乳聚糖 AG2 被证明是生物合成的。多糖的糖组成的变化被证明与α-l-阿拉伯呋喃糖苷酶和β-半乳糖苷酶活性的增加以及细胞内聚半乳糖醛酸酶活性的降低有关。
