Separation of lipoproteins in newborn plasma using an Airfuge ultracentrifuge.

The isolation of lipoprotein fractions in newborn plasma was performed by ultracentrifugation in an Air-driven ultracentrifuge (Airfuge). The purity and recovery of the fractions was checked by quantitation of the apo A1 and B proteins in the supernatant and infranatant fractions, and by gradient gel electrophoresis in 4-30% polyacrylamide gels. The influence of the duration of the ultracentrifugal run, the temperature and method for recovery of the fractions were tested. Under optimal conditions pure VLDL fractions could be isolated at d = 1.006 milligrams, whereas VLDL + LDL isolated at d = 1.063 milligrams were contaminated with HDL and other plasma proteins. Isolation of total lipoproteins at d = 1.21 milligrams enabled recovery of 75% of total plasma lipoproteins, however strongly contaminated by other plasma proteins. These results indicate that the recovery and purity of the lipoprotein fractions isolated in the Airfuge are not comparable to the results obtained in a conventional preparative ultracentrifuge.