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Figure 5
Influence of serum depletion on the recombinant protein yield. (a) Immediately following PEI transfection, cells were grown for 3 d in media supplemented with 2% (lane 1), 1% (lane 2), 0.5% (lane 3), 0.2% (lane 4), 0.1% (lane 5) and 0% (lane 6) serum. Equal amounts of conditioned media were separated by SDS–PAGE and transferred on a nitrocellulose membrane. The membrane was stained with Coomassie Brilliant Blue G-250 after being probed with anti-His antibodies. The overexpressed protein of interest is indicated by a black arrowhead. Bovine serum albumin, the major contaminant from the serum, is indicated by an open arrowhead. Reducing serum levels clearly removes the majority of the contaminant proteins in the medium. However, residual BSA is still present as well as small amounts of some other proteins, probably secreted by the cells. (b) Western blot analysis of the conditioned media confirms that protein yields remain unaffected despite the sudden serum depletion.

Journal logoBIOLOGICAL
CRYSTALLOGRAPHY
ISSN: 1399-0047
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