Chemoenzymic synthesis of (1→3,1→4)-β-D-glucooligosaccharides for subsite mapping of (1→3,1→4)-β-D-glucan endohydrolases
作者:Maria Hrmova、Geoffrey B. Fincher、Josep-Luis Viladot、Antoni Planas、Hugues Driguez
DOI:10.1039/a804711a
日期:——
A series of unsubstituted (1â3,1â4)-β-D-glucooligosaccharides, designed for subsite mapping in which the number of glucosyl-binding subsites and the subsite-binding/transition state activation affinities at individual subsites of plant and bacterial (1â3,1â4)-β-D-glucan 4-glucanohydrolases (EC 3.2.1.73) can be determined, has been synthesised through chemical and enzymic procedures. A recombinant (1â3,1â4)-β-D-glucan 4-glucanohydrolase from Bacillus licheniformis has been used in organic media to catalyse the condensation of 3-O-β-D-glucopyranosyl-β-D-glucopyranosyl fluoride (Glcβ3GlcβF, compound 1) with cellobiose (Glcβ4Glc, 2), cellotriose (Glcβ4Glcβ4Glc, 3), cellotetraose (Glcβ4Glcβ4Glcβ4Glc, 4) and cellopentaose (Glcβ4Glcβ4Glcβ4Glcβ4Glc, 5), to produce the (1â3,1â4)-β-D-glucooligosaccharides, Glcβ3Glcβ4Glcβ4Glc 6, Glcβ3Glcβ4Glcβ4Glcβ4Glc 7, Glcβ3Glcβ4Glcβ4Glcβ4Glcβ4Glc 8, Glcβ3Glcβ4Glcβ4Glcβ4Glcβ4Glcβ4Glc 9. Synthesised oligosaccharides 6â9 were isolated in yields of 15â45%, compared with compound 1. In a second series of syntheses, a cellodextrin phosphorylase (EC 2.4.1.49) from Clostridium thermocellum was used to sequentially transfer glucosyl residues from α-D-glucopyranosyl phosphate 10 to the 4-position of the non-reducing terminus of the trisaccharide Glcβ3Glcβ4Glc 11, to generate the (1â3,1â4)-β-D-glucooligosaccharides, Glcβ4Glcβ3Glcβ4Glc 12, Glcβ4Glcβ4Glcβ3Glcβ4Glc 13, Glcβ4Glcβ4Glcβ4Glcβ3Glcβ4Glc 14 in 14, 10 and 5% yield, respectively, from compound 11.
一系列未取代的(1→3,1→4)-β-D-葡萄糖寡糖被合成,用于亚位点的映射,以确定植物和细菌(1→3,1→4)-β-D-葡聚糖4-葡聚糖水解酶(EC 3.2.1.73)在各个亚位点的葡萄糖结合亚位点的数量以及亚位点结合/过渡态激活亲和力。这些寡糖是通过化学和酶促程序合成的。使用来自枯草芽孢杆菌的重组(1→3,1→4)-β-D-葡聚糖4-葡聚糖水解酶在有机介质中催化3-O-β-D-葡萄糖基-β-D-葡萄糖基氟化物(Glcβ3GlcβF,化合物1)与纤双糖(Glcβ4Glc,2)、纤三糖(Glcβ4Glcβ4Glc,3)、纤四糖(Glcβ4Glcβ4Glcβ4Glc,4)和纤五糖(Glcβ4Glcβ4Glcβ4Glcβ4Glc,5)的缩合反应,生成(1→3,1→4)-β-D-葡萄糖寡糖,Glcβ3Glcβ4Glcβ4Glc 6、Glcβ3Glcβ4Glcβ4Glcβ4Glc 7、Glcβ3Glcβ4Glcβ4Glcβ4Glcβ4Glc 8、Glcβ3Glcβ4Glcβ4Glcβ4Glcβ4Glcβ4Glc 9。合成的寡糖6-9的收率为15-45%,与化合物1相比。在第二系列合成中,使用来自嗜热梭菌的纤维二糖磷酸酶(EC 2.4.1.49)将α-D-葡萄糖基磷酸10的葡萄糖基残基顺序转移到三糖Glcβ3Glcβ4Glc 11非还原末端的4位,生成(1→3,1→4)-β-D-葡萄糖寡糖,Glcβ4Glcβ3Glcβ4Glc 12、Glcβ4Glcβ4Glcβ3Glcβ4Glc 13、Glcβ4Glcβ4Glcβ4Glcβ3Glcβ4Glc 14,分别从化合物11中获得14%、10%和5%的产率。