A novel detection method for quaternization of amino acid and peptide was reported. In this method Ag 2CO 3 was employed instead of KHCO 3 to catalyze the occurrence of quaternization reaction. The absence of metal ions in the reaction system enabled us to in situ detect the quaternizing products by using electrospray ionization mass spectrometry(ESI-MS). We analyzed quaternizing products of six amino acids and two peptides in situ, and obtained the ratio of major product to by-product, which suggests the new method possesses prominent advantages over the old one. This method could offer a potential chance to combine quaternization with mass spectrometry which is helpful for the future use of quaternization reaction in quantitative proteomics.
A simple method for mobilizing the focused zones of capillary isoelectric focusing(CIEF) for single-point detectors was developed, in which a linear polyacrylamide(LPA) coated capillary was connected with an uncoated capillary by an etched porous joint. The etched section allows electrical conductivity but blocks the hydrodynamic flow. The focused zones of mixed proteins was mobilized by this method successfully. Compared with the traditional gravity mobilization step, it was found that this method can mobilize the focused zones more effectively without sacrificing separation efficiency.
A two-dimensional separation platform of capillary isoelectric focusing(CIEF)-capillary zone electrophoresis(CZE) for proteins was constructed by a microdialysis hollow fiber interface. The interface provided ease of fabrication,speed of mass delivering and convenience of column switching. Chrome c was selected to demonstrate the 2D separation systems feasibility and resolving performance. The 2D separation system was found to greatly increase the resolving power and overall peak capacity over those obtained for either dimension alone.
