Detection of squalene in alpha-fetoprotein and fetal serum albumin from bovine

Alpha-fetoprotein and fetal serum albumin have been simultaneously purified from fetal bovine serum by mild procedures utilizing ammonium sulfate, hyd rophobic interaction, immobilized metal (nickel) affinity chromatography, a nd isoelectric focusing. The lipidic extract from each protein was analyzed by gas chromatography and the peak appearing just after the arachidonic ac id was identified as squalene by gas chromatiography-mass spectrometry. Thi s isoprenoid was not detected formerly in these proteins from human, rat, b ovine, and pig. Until recently, in the analysis of the fatty acid compositi on of the alpha-fetoprotein and serum albumin from mammals, a peak has been assigned in the last part of the chromatographic profile, after arachidoni c acid, to docosahexaenoic acid. In the present work, it was found that the peak corresponds to squalene instead of docosahexaenoic acid. Furthermore, we conclude that bovine alpha-fetoprotein and fetal serum albumin carry sq ualene, but not docosahexaenoic acid. These results agree with others obtai ned analyzing the same proteins from chick embryo.