biostudies-literatureShen MNatural Science Foundation of ChinaNational Natural Science Foundation of China420-426https://www.ebi.ac.uk/biostudies/studies/S-EPMC8561817biostudies-literatureUnknown77(Pt 11)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.Acta crystallographica. Section F, Structural biology communicationsCrystal structures of glycogen-debranching enzyme mutants in complex with oligosaccharides.PMC85618173207120531870769Shen MXiang SGong XfalseCrystal structures of glycogen-debranching enzyme mutants in complex with oligosaccharides.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.2021-01-01T00:00:00Z2021 Nov2025-04-04T22:32:13.71Z2025-02-19T03:24:06.174ZS-EPMC85618173472618110.1107/s2053230x2101091810.1107/S2053230X21010918