Example 86
Cysteine engineered monoclonal antibodies were reduced with about a 20-50 fold excess of TCEP (tris(2-carboxyethyl)phosphine hydrochloride or DTT (dithiothreitol) in 4 mM Tris pH 7.3 with 1 mM EDTA for 1 hours at 37° C. The reduced thiomab was diluted and loaded onto a PD-10 column in PBS. The column was eluted with 10 mM PBS pH 7.3. The eluted reduced thiomab was re-established by air oxidation. The thiol/Ab value was checked by determining the reduced antibody concentration form the absorbance at 280 nm of the solution and the thiol concentration by reaction with DTNB (Aldrich, CAS No D8130) and determination of the absorbance at 412 nm.