Characterization of a novel glycosphingolipid, ceramide nonasaccharide, isolated from spermatozoa of the fresh water bivalve, Hyriopsis schlegelii.

A new glycosphingolipid, provisionally named Lipid III in our previous work (Hori, T., Sugita, M., Kanbayashi, J., and Itasaka, O. (1977) J. Biochem. (Tokyo) 81, 107-114), was extracted and purified from the spermatozoa of the fresh water bivalve, Hyriopsis schlegelii. The yield of the glycolipid was 1.8 mg/g dry weight of the spermatozoan preparation. Its chemical structure was characterized by compositional analysis, partial acid hydrolysis, methylation analysis, and proton nuclear magnetic resonance spectroscopy. The following structure is proposed: 3-O-MeFuc alpha 1 leads to 2.3-O-MeXyl beta 1 leads to 4(3-O-MeGalNAc alpha 1 leads to 3)Fuc alpha 1 leads to 4GlcNAc beta 1 leads to 2Man alpha 1 leads to 3(Xyl beta 1 leads to 2)Man beta 1 leads to 4Glc beta 1 leads to 1Cer. This glycolipid contains the same backbone as the pentaglycosyl ceramide (Lipid II) reported previously (Hori, T., Takeda, H., Sugita, M., and Itasaka, O. (1977) J. Biochem. (Tokyo) 82, 1281-1285). Lipid III is structurally related to Lipid II by linking it with a fucose and three kinds of O-methyl sugars, namely, 3-O-methylxylose, 3-O-methylfucose, and 3-O-methyl-N-acetylgalactosamine, through an internal fucose moiety. Unlike most vertebrate glycolipids, Lipid III appears to be unique in having an internal fucose and O-methyl sugars as well as mannose. To our knowledge, this is the first instance for the natural occurrence of 3-O-mehylxylose. Aliphatic constituents of the lipid are palmitic acid and stearic acid as the principal fatty acids, and octadeca-4-sphingenine as the major long chain base.