Protein analysis with large volume sample stacking with an electrosmotic flow pump: a potential approach for proteomics

Large volume sample stacking using electrosmotic flow pump (LVSEP) in capillary electrophoresis is a useful tool for on-line concentration of low-abundant protein samples for proteomics research. While the stacking of only small anions with high pK(a) values has been reported at low pH buffers (pH < 4), protein samples (trypsin inhibitor and a-lactalbumin) with high pI values (pI > 4) were stacked successfully in our system using LVSEP. Initially, the whole column of the SIL, or LPA-coated capillary was filled with protein samples (similar to1 mug/ml), then a high voltage was applied without polarity switching with high pH buffer (pH 8.5). An enhancement factor of more than 100 times was achieved compared to the conventional pressure injection method. (C) 2001 Elsevier Science B.V. All rights reserved.