The notion that sugar structures are difficult to pin down isn’t new, says Carolyn Bertozzi, a glycobiologist at Stanford University in Palo Alto, California, who was not involved in the study. Sugar molecules’ small size and flexibility can make it hard to identify their exact conformation. Still, the new work quantifies the scale of the problem and so “delivers an important message,” Bertozzi says. The incorrect structures, she adds, “reveal widespread ignorance of chemistry and glycobiology, or at least profound inattention to the [sugar] component” of protein structure.