On-Column Ligand/Receptor Derivatization Coupled to Affinity Capillary Electrophoresis

The coupling of on-column derivatization of small molecules to affinity capillary electrophoresis (ACE) has only been realized during the past 5 yr. In this technique, multiple zones of reagent(s) and ligand or receptor are injected into the capillary column. Upon electrophoresis, zones of sample overlap, yielding product. Continued electrophoresis results in the product overlapping with receptor (or ligand, if the receptor was derivatized), thereby causing a shift in migration time of the compound in question. Subsequent Scatchard analysis using noninteracting standards realizes a binding constant. Herein, we describe the use of on-column-ligand and receptor derivatization coupled to partial-filling ACE (PFACE) to probe the binding of vancomycin (Van) from Streptomyces orientalis and teicoplanin (Teic) from Actinoplanes teicomyceticus to D-Ala-D-Ala terminus peptides.