High density lipoprotein (HDL), and not albumin, is the major palmitate binding protein in New Zealand long-finned (Anguilla dieffenbachii) and short-finned eel (Anguilla australis schmidtii) plasma

Abstract

Plasma from two members of the teleost Anguillidae family, the New Zealand long-finned (Anguilla dieffenbachii) and short-finned eels (Anguilla australis schmidtii), were examined. Agarose gel electrophoresis showed both species had a major anionic diffuse protein band migrating at approximately the same position as human albumin, and autoradiography showed this protein bound [14C]palmitic acid, but not 63Ni2+. Cellulose acetate electrophoresis followed by Oil Red O staining suggested that this band was a lipoprotein. Two-dimensional electrophoresis of plasma showed the absence of a significant albumin band at approx. 65 kDa, and that the palmitate binding band appeared to be composed of at least three proteins, with the major protein running at 30 kDa. N-Terminal sequencing of the palmitate binding band indicated major sequences of DAPAPP(S)QLED- for long-finned eel and DAPAPPSQLEHV- for short-finned eel, confirming their identities as apo-AI, the major apolipoprotein of high density lipoprotein (HDL). When ultracentrifugation was used to separate the lipoproteins of each species, the anionic palmitate binding protein was found solely in the lipoprotein fractions. There was no evidence of albumin in plasma from either eel, and it appears that in its absence HDL takes on the role of fatty acid transport.