Isolation and characterization of ganglioside GM1b from normal human brain.

A sialidase-susceptible monosialoganglioside was isolated from normal human brain by DEAE-Sephadex A-25 and Iatrobeads column chromatography. The yield of this ganglioside was about 6 mg per whole brain. Its structure was elucidated by sugar analysis, sialidase digestion, permethylation, and proton NMR studies. This ganglioside had carbohydrate, fatty acid, and long-chain base compositions identical to those of brain GM1a. However, the sialosyl residue was found to be linked (alpha 2-3) to the terminal galactosyl residue of the asialo-GM1a backbone. The complete structure of this ganglioside was therefore identified as GM1b or IV3NeuAcGgOse4Cer.