Immunochemical Studies on Phosphonolipids (Ceramide 2-Aminoethylphosphonate)

A specific antiserum against ceramide 2-aminoethylphosphonate (CAEPn) from spermatozoa of the fresh-water bivalve, Hyriopsis schlegelii, was raised in rabbit. The IgG fraction prepared from this antiserum agglutinated the liposomes containing CAEPn, but not those containing other phosphono-and phospholipids. The antigen specificity of anti-CAEPn IgG was further examined by enzyme linked immunosorbent assay (ELISA) to reveal antigenic determinants being C-P bond, free amino group and ceramide portion (the acid-amide bond) possibly. Immunoquantitative analysis of CAEPn in several fresh- and marine-water shellfish by ELISA showed these shellfish to contain CAEPn in amounts 5 to 40% that of the alkali-stable lipid (sphingolipid fraction).