Structures of N-linked sugar chains expressed mainly in mouse brain.

Sugar chains were liberated from mouse tissues (liver, heart, spleen, kidney, thymus, cerebrum, cerebellum, and brain stem) by hydrazinolysis. After acetylation of the free amino groups, the sugar chains released were pyridylaminated. Pyridylamino (PA-) derivatives of the sugar chains from each tissue were fractionated by anion-exchange high-performance liquid chromatography (HPLC) according to their negative charges. Fractions containing PA-neutral sugar chains thus obtained were separated successively by size-fractionation HPLC and reversed-phase HPLC. Two sugar chains that were more abundant in neural tissues than in other tissues were purified. The structures of the two sugar chains were determined by sugar composition analysis, sequential exoglycosidase digestion, and methylation analysis. The proposed structures are shown below. A structure with n = 1 was found in the cerebrum, cerebellum, and brain stem. A structure with n = 0 was abundant in the cerebrum and brain stem, but less so in the cerebellum. [formula: see text]