This work demonstrates that a highly linear, controllable and wide-ranged pH-gradient can be generated through an ion-exchange chromatography (IEC) column. Such a pH-gradient anion-exchange chromatography was evaluated with 17 model proteins and found that acidic (pI <6) and basic (pI > 8) proteins elute roughly at their pI, whereas neutral proteins (pI 6–8) elute at pH 8–9 regardless their pI values. Because of the flat nature of protein titration curves from pH 6 to 9, neutral proteins indeed exhibit nearly zero net charge at pH 9. The elution-pH in pH-gradient IEC or the titration curve, but not the pI, was identified as the key parameter for pH optimization of preparative IEC in a fast and rational way. The pH-gradient IEC was also applied and found to be an excellent analytical tool for the fractionation of crude protein mixtures.
|Journal||Journal of Chromatography. A, Including electrophoresis and other separation methods|
|Publication status||Published - 2007|
- performance liquid-chromatography
- rapid separation