Affinity capillary electrophoresis to examine receptor-ligand interactions.

Afffinity capillary electrophoresis (ACE) is a new analytical technique that has been shown to be an efficient and accurate tool in studying biomolecular noncovalent interactions and determining binding and dissociation constants of formed complexes. ACE uses as its basis the change in migration time of a receptor upon binding to a ligand found in the electrophoresis buffer. Subsequent Scatchard analysis using noninteracting markers realizes a binding constant. Herein, ACE and three modifications in the technique, partial-filling ACE (PFACE), flow through PFACE (FTPFACE), and multiple-step ligand injection ACE (MSLIACE) are used to probe the binding of ristocetin A (Rist A) and vancomycin (Van) from Streptomyces orientalis to D-Ala-D-Ala terminus peptides and carbonic anhydrase B (CAB, E.C.4.2.1.1) to arylsulfonamides.

Partial-filling affinity capillary electrophoresis.

Partial-filling affinity capillary electrophoresis (PFACE) is used to examine the binding interactions between two model biological systems: D-Ala-D-Ala terminus peptides to the glycopeptide antibiotic vancomycin (Van) from Streptomyces orientalis, and arylsulfonamides to carbonic anhydrase B (CAB, EC 4.2.1.1, bovine erythrocytes). Using these two systems, modifications in the PFACE technique are demonstrated including flow-through PFACE (FTPFACE), competitive flow-through PFACE (CFTPFACE), on-column ligand synthesis PFACE (OCLSPFACE), and multiple-step ligand injection PFACE (MSLIPFACE). In PFACE small plugs of sample are injected into the capillary column and an equilibrium is established between receptor and ligand during electrophoresis. Binding constants are then obtained by Scatchard analysis using changes in the migration time of the receptor/ligand on changing the concentration of the ligand/receptor. Data demonstrating the quantitative potential of these methods are presented. This review focuses on the unique capabilities of the different PFACE techniques as applied to two model biological systems.