M. Kats et al., PH-DEPENDENT ISOFORM TRANSITIONS OF A MONOCLONAL-ANTIBODY MONITORED BY MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY, Analytical chemistry, 69(3), 1997, pp. 338-343
Within the pH range 2-12, the monoclonal chimeric antibody BR96 can be
separated into one to five isoforms by micellar electrokinetic capill
ary chromatography (MECC). The distribution of the immunoglobulin betw
een these isoforms is pH dependent and apparently reversible, Some of
the changes in the electrophoretic profile are represented by alterati
ons in the immunoglobulin secondary structure, MECC and CD data demons
trate that, in other cases, differences in electrophoretic mobilities
of the intact and acid-stressed antibody molecules were not due to dif
ferences in the ionization of the protein functional Groups or changes
ire secondary structure, but rather resulted from differences in the
exposure of the molecule's structural elements to the solvent The resu
lts indicate that the interaction of the isoforms with sodium dodecyl
sulfate micelles plays a crucial role in MECC isoform separations, The
formation of analyte-micelle complexes was postulated to make electro
phoretic mobilities, especially of large protein molecules, susceptibl
e to subtle conformational changes that are not detectable by other me
thods.