Figure 1.
Purified human properdin and recombinant maltose-binding protein (MBP)-thrombospondin repeats (TSR) 4+5. (A) Properdin was purified from human plasma. Filtered plasma was applied to a non-immune IgG-Sepharose column, then to a mouse monoclonal anti-properdin Sepharose column; properdin was eluted with 3 M MgCl2. The eluted samples were dialyzed against HEPES buffer (10 mM HEPES, 140 mM NaCl, 0.5 mM EDTA, pH 7.4) overnight at 4°C. Contaminants were removed by applying the protein to a Q Sepharose column, and the product appears as a single band on SDS-PAGE and western blot at about 55 kDa. (B) MBP-TSR4+5 was purified via an amylose resin column, and the purified fusion protein also appears on SDS-PAGE as a band of about 55 kDa.