Electrophoresis of megaDalton proteins inside colloidal silica.

With the growth of the biopharmaceutical industry, there is a need for rapid size-analysis of proteins on the megaDalton scale. The large pore sizes needed for such separations cannot be easily reached by pushing the current limits of size-exclusion chromatography or gel electrophoresis. The concept detailed here is the formation of arbitrarily wide pores by packing nonporous colloidal silica in capillaries. This method can be called packed-capillary electrophoresis, or "pCE". Electrophoresis of protein standards (11-155 kDa) by pCE, using 345 nm diameter particles in 100 µm diameter capillaries, gives 2x higher resolution than a typical PAGE gel in 1/6 of the time. The electropherograms show that pCE is highly efficient, with half-micrometer plate heights for all seven standards, giving 105 plates for a 50 mm length. The large pore radius of 65 nm enables baseline resolution of proteins of 0.72, 1.048 and 1.236 MDa in less than 15 min. The short separation time of pCE is attributed to the absence of small pores that restrict protein migration in gels. The pCE separation is applied to the analysis of a stressed pharmaceutical-grade IgG4 sample, giving unprecedented baseline resolution of monomer, dimer, trimer and tetramer in less than 10 min.

Organohalogen Contaminants and Vitamins in Northern Fur Seals (Callorhinus ursinus) Collected During Subsistence Hunts in Alaska.

During native subsistence hunts from 1987 to 2007, blubber and liver samples from 50 subadult male northern fur seals (Callorhinus ursinus) were collected on St. Paul Island, Alaska. Samples were analyzed for legacy persistent organic pollutants (POPs), recently phased-out/current-use POPs, and vitamins. The legacy POPs measured from blubber samples included polychlorinated biphenyl congeners, DDT (and its metabolites), chlorobenzenes, chlordanes, and mirex. Recently phased-out/current-use POPs included in the blubber analysis were the flame retardants, polybrominated diphenyl ethers, and hexabromocyclododecanes. The chemical surfactants, perfluorinated alkyl acids, and vitamins A and E were assessed in the liver samples. Overall, concentrations of legacy POPs are similar to levels seen in seal samples from other areas of the North Pacific Ocean and the Bering Sea. Statistically significant correlations were seen between compounds with similar functions (pesticides, flame retardants, vitamins). With sample collection spanning two decades, the temporal trends in the concentrations of POPs and vitamins were assessed. For these animals, the concentrations of the legacy POPs tend to decrease or stay the same with sampling year; however, the concentrations of the current-use POPs increased with sampling year. Vitamin concentrations tended to stay the same across the sampling years. With the population of northern fur seals from St. Paul Island on the decline, a detailed assessment of exposure to contaminants and the correlations with vitamins fills a critical gap for identifying potential population risk factors that might be associated with health effects.