The large-scale production of oligosaccharides is a daunting task, hampering the study of the role of glycans in vivo and the testing of the efficacy of novel glycan-based drugs. Glycosynthases, mutated glycosidases that synthesize oligosaccharides in high yields, are becoming important chemo-enzymatic tools for the production of oligosaccharides. However, while β-glycosynthase can be produced with a rather well-established technology, examples of α-glycosynthases are thus far limited only to enzymes from glycoside hydrolase 29 (GH29), GH31 and GH95 families. α-l-Fucosynthases from GH29 use convenient glycosyl azide derivatives as a strategic alternative to glycosyl fluoride donors. However, the general applicability of this method to other α-glycosynthases is not trivial and remains to be confirmed. Here, β-d-galactopyranosyl azide was converted to α-galacto-oligosaccharides with good yields and high regioselectivity, catalyzed by a novel α-galactosynthase based on the GH36 α-galactosidase from the hyperthermophilic bacterium Thermotoga maritima. These results open a new avenue to the practical synthesis of biologically interesting α-galacto-oligosaccharides and demonstrate more widespread use of β-glycosyl-azide as donors, confirming their utility to expand the repertoire of glycosynthases.
                                    寡糖的大规模生产是一项艰巨的任务,阻碍了聚糖在体内作用的研究和新型聚糖药物功效的测试。糖合酶是高产合成
寡糖的突变糖苷酶,正在成为
寡糖生产的重要
化学酶工具。然而,虽然 β-糖合酶可以通过相当成熟的技术生产,但 α-糖合酶的例子迄今为止仅限于来自糖苷
水解酶 29 (GH29)、GH31 和 GH95 家族的酶。 GH29 的 α-l-岩藻糖合成酶使用方便的糖基
叠氮衍
生物作为糖基
氟化物供体的战略替代品。然而,该方法对其他 α-糖合酶的普遍适用性并非微不足道,仍有待证实。在这里,β-d-
吡喃半
乳糖基
叠氮化物被一种新型 α-半
乳糖合酶催化,以良好的产率和高区域选择性转化为 α-低聚半
乳糖,该酶基于来自超嗜热细菌海栖热袍菌的 GH36 
α-半乳糖苷酶。这些结果为实际合成具有
生物学意义的α-低聚半
乳糖开辟了一条新途径,并证明了β-糖基
叠氮化物作为供体的更广泛用途,证实了它们在扩展糖合酶库方面的效用。