Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, 22 Qixiangtai Road, Heping District, Tianjin 300070, People's Republic of China.
Acta Crystallogr F Struct Biol Commun. 2021 Nov 1;77(Pt 11):420-426. doi: 10.1107/S2053230X21010918. Epub 2021 Oct 29.
Debranching is a critical step in the mobilization of the important energy store glycogen. In eukaryotes, including fungi and animals, the highly conserved glycogen-debranching enzyme (GDE) debranches glycogen by a glucanotransferase (GT) reaction followed by a glucosidase (GC) reaction. Previous work indicated that these reactions are catalyzed by two active sites located more than 50 Å apart and provided insights into their catalytic mechanisms and substrate recognition. Here, five crystal structures of GDE in complex with oligosaccharides with 4-9 glucose residues are presented. The data suggest that the glycogen main chain plays a critical role in binding to the GT and GC active sites of GDE and that a minimum of five main-chain residues are required for optimal binding.
去分枝是动员重要能量储存物糖原的关键步骤。在真核生物中，包括真菌和动物，高度保守的糖原分支酶（GDE）通过糖基转移酶（GT）反应和随后的糖苷酶（GC）反应来分支糖原。以前的工作表明，这些反应是由两个相隔超过 50 Å 的活性位点催化的，并为它们的催化机制和底物识别提供了见解。在这里，展示了 GDE 与具有 4-9 个葡萄糖残基的寡糖复合物的五个晶体结构。数据表明，糖原主链在与 GDE 的 GT 和 GC 活性位点结合中起关键作用，并且至少需要五个主链残基才能实现最佳结合。
