Oligosaccharide recognition and binding to the carbohydrate binding module of AMP-activated protein kinase

The AMP-activated protein kinase (AMPK) contains a carbohydrate-binding module (β1-CBM) that is conserved from yeast to mammals. β1-CBM has been shown to localize AMPK to glycogen in intact cells and in vitro. Here we use Nuclear Magnetic Resonance spectroscopy to investigate oligosaccharide binding to 15N labelled β1-CBM. We find that β1-CBM shows greatest affinity to carbohydrates of greater than five glucose units joined via α,1 → 4 glycosidic linkages with a single, but not multiple, glucose units in an α,1 → 6 branch. The near identical chemical shift profile for all oligosaccharides whether cyclic or linear suggest a similar binding conformation and confirms the presence of a single carbohydrate-binding site.