Contemporary chemoenzymatic approaches can provide highly complex multi-antennary N-linked glycans. These procedures are, however, very demanding and typically involve as many as 100 chemical steps to prepare advanced intermediates that can be diversified by glycosyltransferases in a branch-selective manner to give asymmetrical structures commonly found in nature. Only highly specialized laboratories can perform such syntheses, which greatly hampers progress in glycoscience. Here we describe a biomimetic approach in which a readily available bi-antennary glycopeptide can be converted in ten or fewer chemical and enzymatic steps into multi-antennary N-glycans that at each arm can be uniquely extended by glycosyltransferases to give access to highly complex asymmetrically branched N-glycans. A key feature of our approach is the installation of additional branching points using recombinant MGAT4 and MGAT5 in combination with unnatural sugar donors. At an appropriate point in the enzymatic synthesis, the unnatural monosaccharides can be converted into their natural counterpart, allowing each arm to be elaborated into a unique appendage.

当代化学酶学方法可以提供高度复杂的多天线N-连接聚糖。然而，这些程序非常苛刻，并且通常涉及多达100个化学步骤来制备高级中间体，该中间体可以通过糖基转移酶以支链选择性的方式多样化，从而获得自然界普遍存在的不对称结构。只有高度专业的实验室才能进行此类合成，这极大地阻碍了糖科学的进展。在这里，我们描述了一种仿生方法，其中一种容易获得的双触角糖肽可以在十个或更少的化学和酶促步骤中转化为多触角N-聚糖，在每个臂上可以通过糖基转移酶独特地延伸以提供对高度复杂的不对称通道的访问分枝的N-聚糖。我们方法的关键特征是使用重组MGAT4和MGAT5与非天然糖供体的结合来安装其他分支点。在酶促合成的适当时机，可以将非天然单糖转化为其天然对应物，从而使每个臂都可以精加工成独特的附件。