Biomolecular interactions are of fundamental importance in biological systems. For example, protein-carbohydrate interactions involve in a variety of cellular phenomena such as cellular recognition, cell adhesion, and cellular uptake. DNA-protein interactions play central roles in a number of basic cellular processes including DNA replication, DNA repair, transcription and recombination. Consequently, developing efficient and reliable methods to study these interactions is very critical for understanding some complex cellular functions and mechanisms. Classic electrophoresis methods such as electrophoretic mobility shift assay (EMSA) and affinity electrophoresis are very frequently used tools for this purpose. For example, in the field of molecular biology, EMSA is widely used for detection of the sequence-specific interactions between proteins and DNA. Capillary electrophoresis (CE) is a relatively new technique with high resolution, high speed, precise quantification and full automation, nowadays it also becomes an important method for the study of biomolecular interactions.
Currently, our work in this field involves developing CE methods to characterize protein-DNA and protein-lipid interactions. It is well known that CE has been popularly used for the investigation of protein-ligand, protein-drug and protein-carbohydrate bindings. However, application of CE in the study of protein-DNA or protein-lipid interactions still receives little attention. Our aim is to establish highly sensitive capillary electrophoretic mobility shift assay (CEMSA) or affinity capillary electrophoresis (ACE) method to measure these interactions. Our recent studies have indicated that, by using these methods with ultra-sensitive sheath flow LIF detector, both qualitative and quantitative information could be obtained for the interactions between nanomolar biomolecules. On the other hand, we are also developing ACE methods to study the binding of drugs and their metabolites to specific proteins. UV detector is often used for the existed ACE methods for studying protein-drug binding. Unfortunately, this detector lacks sensitivity and it limits the application of ACE method. Hence, we expect to establish sensitive ACE-LIF (APCE) method for drug binding study. By utilizing high sensitivity of LIF detection and ultra-small sample volume of CE, it is possible for us to investigate the effects of protein-drug binding on drug uptake by cells.