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Precipitation and recovery of proteins from culture supernatants using zinc
1Molecular Biology Research, Upjohn Company, Kalamazoo, Michigan 49007.
Abstract:
A convenient method for the concentration of proteins from culture supernatants is described. Heterologous gene products expressed and secreted into the culture medium by Saccharomyces cerevisiae, Chinese hamster ovary cells (CHO), and Bacillus subtilis were precipitated out of solution by the addition of millimolar concentrations of zinc chloride. Porcine urokinase secreted by S. cerevisiae, the tissue-type plasminogen activator analog FK2P secreted by CHO cells, and human interleukin-1 beta secreted by B. subtilis were all precipitated by zinc ions. Both urokinase and FK2P were precipitated with as low as 2 mM zinc, with recovery of activity in the precipitate approaching 100%.