Novel polysialogangliosides of skate brain.

The gangliosides in the brain of a cartilaginous fish, skate (Bathyraja smirnovi), have been isolated and characterized by means of methylation analysis, antibody binding, enzymatic hydrolysis and MALDI-TOF MS. In addition to gangliosides with known structures (GM2, fucosyl-GM1, GD3, GD2, GT3 and GT2), five polysialogangliosides were isolated and characterized as having the following structures. (1) IV³NeuAc, III⁶NeuAc, II³NeuAc-Gg₄Cer; (2) IV³NeuAc₂, III⁶NeuAc, II³NeuAc-Gg₄Cer; (3) IV³NeuAc, III⁶NeuAc, II³NeuAc₂-Gg₄Cer; (4) IV³NeuAc, III⁶NeuAc, II³NeuAc₃-Gg₄Cer; and (5) IV³NeuAc₂, III⁶NeuAc, II³NeuAc₃-Gg₄Cer. These structures are ‘hybrid-type’ which comprise combinations of α-series and either a, b or c-series structures. Three gangliosides (2), (4) and (5), were novel. The main features of the ganglioside composition of skate brain were an abundance of gangliotriaosyl species, a lack of gangliotetraosyl species (except fucosyl-GM1), and an abundance of hybrid-types. These characteristics closely resemble those in shark brain which we reported previously [Nakamura, K., Tamai, Y. & Kasama, T. (1997) Neurochem. Int. 30, 593–604]. Two of the hybrid-type gangliosides (1) and (4), were examined for their neuritogenic activity toward cultured neuronal cells (Neuro-2A), and were found to have more potent activity than nonhybrid-type gangliosides such as GM1. [ABSTRACT FROM AUTHOR]