Abstract
Industrial scale production of therapeutic monoclonal antibodies (mAbs)
is commonly achieved with Protein A chromatography, a process that
requires exposure of the antibody to strongly acidic conditions during
the eluting step. Exposure to acid inactivates virus contaminants but
may, in parallel, lead to antibody aggregation that must be eliminated
or kept at acceptably low levels. This report seeks to provide a
practical method for overcoming a long-standing problem. We show how
Brij-O20 detergent micelles, conjugated by the amphiphilic
[(bathophenanthroline)3:Fe2+]
complex in the presence of amino acid monomers: phenylalanine (Phe),
tyrosine (Tyr), tryptophan (Trp), isoleucine (Ile) or valine (Val),
efficiently capture polyclonal human IgG (hIgG) at neutral pH and allow
its recovery by extraction either at pH 4 (85-97% yield) or at pH 6.3
(72-84% yield). Of the five amino acid monomers surveyed, Phe or Tyr
produced the highest overall process yield at both pH 4 and 6.3. The
monomeric state of the purified hIgG’s was confirmed by dynamic light
scattering (DLS). Potential advantages of the purification method are
discussed.