ISOLATION OF 3 NOVEL CHOLINERGIC NEURON-SPECIFIC GANGLIOSIDES FROM BOVINE BRAIN AND THEIR IN-VITRO SYNTHESES

In the present study, three extremely minor but novel Chol-1 antigens, termed X1, X2, and X3 have been isolated from bovine brain gangliosid es. Based on the results of sialidase degradation, TLC-immunostaining with anti-Chol-1 antibody and fast atom bombardment mass spectrometry, their chemical structures were identified as: III(6)NeuAc-GgOse4Cer ( X1: GM1 alpha) III(6)NeuAc,II(3)NeuAc-GgOse4Cer (X2: GD1a alpha) III(6 )NeuAc,II(3)NeuAc-NeuGc-GgOse4Cer (X3: GT1b alpha) The yields of GM1 a lpha, GD1a alpha, and GT1b alpha, were approximately 150, 20, and 10 m u g, respectively, from 10 g of the bovine brain ganglioside mixture. In conjunction with our previous observations, all gangliosides with a nti-Chol-1 reactivity were found to contain a common sialyl alpha 2-6 N-acetylgalactosamine residue, indicating that this unique sialyl link age is the specific antigenic determinant. We subsequently examined th e biosyntheses of the three novel Chol-1 gangliosides using rat liver Golgi fraction as an enzyme source. The results showed that GM1 alpha, GD1a alpha, and GT1b alpha were synthesized from asialo-GM1, GM1a, an d GD1b, respectively, by the action of a GalNAc alpha 2-6sialyltransfe rase.