Comparative study of analytical techniques for determining protein charge.
As interest in high-concentration protein formulations has increased, it has become apparent that routine, accurate protein charge measurements are necessary. There are several techniques for charge measurement, and a comparison of the methods is needed. The electrophoretic mobility, effective charge, and Debye-Hückel-Henry charge have been determined for bovine serum albumin, and human serum albumin. Three different electrophoretic methods were used to measure the electrophoretic mobility: capillary electrophoresis, electrophoretic light scattering, and membrane confined electrophoresis. In addition, the effective charge was measured directly using steady-state electrophoresis. Measurements made at different NaCl concentrations, pH, and temperatures allow comparison with previous charge estimates based on electrophoresis, Donnan equilibrium, and pH titration. Similar charge estimates are obtained by all of the methods. The strengths and limitations of each technique are discussed, as are some general considerations about protein charge and charge determination.
CAMIS, University of New Hampshire, St. Durham, New Hampshire.
Dana I
DI
Filoti
Late Stage Pharmaceutical and Device Development, Genentech, Inc., South San Francisco, California.
Steven J
SJ
Shire
Late Stage Pharmaceutical and Device Development, Genentech, Inc., South San Francisco, California.
Sandeep
S
Yadav
CAMIS, University of New Hampshire, St. Durham, New Hampshire.
Thomas M
TM
Laue
D000818:Animals; D004586:Electrophoresis / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D009994:Osmolar Concentration; D011506:Proteins / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry*; D013696:Temperature
D011506:Proteins; D012709:Serum Albumin
colloid; electrophoresis; protein charge; protein formulation; proteins; solubility