Mild alkaline hydrolysis of some 7-O-flavone glycosides. Application to a novel access to rutinose heptaacetate
作者:Jérôme Quintin、Guy Lewin
DOI:10.1016/j.tetlet.2005.04.085
日期:2005.6
2-hydroxy group trans to the sugar–aglycon bond as in β-D-glucosides or rutinosides, hydrolysis occurred at room temperature under very mild conditions. Application to a novel preparation of rutinose heptaacetate by hydrolysis of a diosmin derivative is described.
α-<scp>L</scp>
-Rhamnosyl-β-<scp>D</scp>
-glucosidase (Rutinosidase) from <i>Aspergillus niger</i>
: Characterization and Synthetic Potential of a Novel Diglycosidase
We report the first heterologous production of a fungal rutinosidase (6‐O‐α‐L‐rhamnopyranosyl‐β‐D‐glucopyranosidase) in Pichia pastoris. The recombinant rutinosidase was purified from the culture medium to apparent homogeneity and biochemically characterized. The enzyme reacts with rutin and cleaves the glycosidic linkage between the disaccharide rutinose and the aglycone. Furthermore, it exhibits
Operational stabilization of fungal α-rhamnosyl-β-glucosidase by immobilization on chitosan composites
作者:Lucrecia Piñuel、Laura S. Mazzaferro、Javier D. Breccia
DOI:10.1016/j.procbio.2011.09.014
日期:2011.12
order to increase the substrate solubility, and 80% activity was retained (1 h, 60 °C) in contrast with the complete inactivation of the free form. The stability of the immobilized catalyst was extended to metalcatalyzed oxidation where the enzyme was fully preserved in harsh conditions such as 1 mM CuSO4 at 60 °C during 1 h.
摘要 枝顶孢属的二糖苷酶 α-鼠李糖基-β-葡萄糖苷酶。DSM24697 通过吸附和交联进行固定。筛选的支持物包括壳聚糖复合材料珠粒(明胶、阿拉伯胶、硅胶)、环氧活化的琼脂糖和壳聚糖,以及大孔聚乙烯醇冷冻凝胶。选择壳聚糖-硅胶珠是因为获得了最高的固定效率和它们的形态特性(直径 1.67 ± 0.99 mm,圆形度 0.81 ± 0.05)。固定化的优化——用聚乙烯亚胺包被,改变酶负载——将固定化效率提高了 18%。该酶的实际应用涉及低水溶性底物。固定化酶的 KM 更高——8 mM 对 1。8 mM 橙皮苷作为游离酶——表明底物扩散限制了酶促反应。添加溶剂二甲基亚砜 (50%, v/v) 以增加底物溶解度,与游离形式的完全失活相比,保留了 80% 的活性(1 小时,60°C)。固定化催化剂的稳定性扩展到金属催化氧化,其中酶在恶劣条件下完全保存,例如 1 mM CuSO4 在 60°C 下 1
AbstractFree rutinose was prepared by enzymatic hydrolysis of rutin using defatted seedmeal from tartary buckwheat. This disaccharide was used as substrate in spectrophotometric assay of α-l-rhamnosidase. The assay is based on hydrolysis of rutinose and subsequent determination of releasedglucose by a standard glucose oxidase assay kit. The method is easy to perform and requires no expensive equipment
Dracopalmaside, a New Flavonoid from Dracocephalum palmatum
作者:D. N. Olennikov、N. K. Chirikova
DOI:10.1007/s10600-015-1493-3
日期:2015.11
Phytochemical studies of the aerial part of Dracocephalum palmatum (Lamiaceae) isolated the new flavonoid dracopalmaside that was identified based on UV, MS, and NMR spectral data as luteolin-7,4′-di-O-α -Lrhamnopyranosyl-(1→6)-β-D-glucopyranoside (luteolin-7,4′-di-O-rutinoside) and the two known compounds cynarotriside and luteolin-7,4′-di-O-glucoside.