Multiple injection affinity capillary electrophoresis (MIACE)

CHED 193

Violet Calderon, Department of Chemistry and Biochemistry, California State University Los Angeles, 5151 State University Dr, Los Angeles, CA 90032 and Frank A. Gomez, fgomez2@calstatela.edu, Chemistry and Biochemistry, California State University, Los Angeles, 5151 State University Drive, Los Angeles, CA 90032.
We describe two types of multiple-injection affinity capillary electrophoresis (MIACE). In the first technique on-column ligand derivatization and partial filling MIACE are coupled to each other to determine multiple binding constants (Kb). In this technique, a series of plugs containing substrate and reagents are injected followed by an increasing concentration of vancomycin (Van) and electrophoresed. Differential mobilities cause plugs to overlap resulting in the formation of multiple zones of product which then overlap with the zone of Van. In the second technique a Kb is determined for peptides of similar charge and mass to antibiotics. In this technique, separate plugs of standard, peptides and buffer, and then increasing concentration of antibiotic are injected and electrophoresed. Peptides migrate through the capillary column at similar electrophoretic mobilities but remain as distinct zones due to the buffer plugs. Shifts in the migration time of peptides relative to standards are used to estimate Kb.