Isolation and characterization of a 4-O-methylglucuronic acid-containing glycosphingolipid from spermatozoa of a fresh water bivalve, Hyriopsis schlegelii.

A novel glycosphingolipid, provisionally named Lipid IV (Hori, T., Sugita, M., Ando, S., Kuwahara, M., Kumauchi, K., Sugie, E., and Itasaka, O. (1981) J. Biol. Chem. 256, 10979-10985), was obtained from spermatozoa of the fresh water bivalve, Hyriopsis schlegelii. The yield of the glycolipid was 2.2 mg/g of dried spermatozoa. The structure of the glycolipid was elucidated by partial hydrolysis, permethylation analysis, and proton nuclear magnetic resonance. The following structure is proposed: GlcA4Me beta 1-4(GalNAc3Me alpha 1-3)Fuc alpha 1-4GlcNAc beta 1-2Man alpha 1-3(Xyl beta 1-2)Man beta 1-4Glc beta 1-Cer. The acidic glycolipid is unique in containing 4-O-methylglucuronic acid as well as an internally located fucose. Palmitic acid, stearic acid, and C18-sphingosine are the major aliphatic components. This composition is similar to those of other neutral spermatozoan glycolipids, Lipid I (Hori, T., Sugita, M., Kanbayashi, J., and Itasaka, O. (1977) J. Biochem. (Tokyo) 81, 107-114) and Lipid II (Hori, T., Takeda, H., Sugita, M., and Itasaka, O. (1977) J. Biochem. (Tokyo) 82, 1281-1285), suggesting a possible metabolic relationship among them.