Capillary electrophoretic reactor for estimation of spontaneous dissociation rate of Trypsin-Aprotinin complex

Assessment of the structural change of DNA by binding with a small molecule based on capillary sieving electrophoresis

In this study, capillary sieving electrophoresis (CSE) using polymer solutions was used to evaluate the structural changes in nucleic acids upon complexation with small molecules. As the model target and nucleic acids, L-tyrosinamide (Tyr-Am) and its aptamer, which is a type of DNA specifically binding to Tyr-Am, were selected. CSE was conducted using a capillary filled with background solution (BGS) containing hydroxypropyl cellulose (HPC) as a sieving matrix. When Tyr-Am or tyrosine was added to the BGS in CSE, the ratio of mobility differences of the Tyr-Am-aptamer complex increased compared to that of the free aptamer without the addition of Tyr-Am. In contrast, when other amino acids or their analogs were added, results showed no apparent change or decreases in electrophoretic mobility. These results indicate that the proposed method can be applied to assess structural changes in nucleic acids that target small molecules.

Evaluation of the interactions between oligonucleotides and small molecules by partial filling-nonequilibrium affinity capillary electrophoresis

Recently, high-throughput analysis with minimal reagent consumption has been desired to assess interactions between drug candidates and disease-related oligonucleotides. To realize an ideal assay for drug screening, a rapid assay based on affinity capillary electrophoresis was generated to reduce the consumption of samples/reagents by a partial-filling technique under nonequilibrium conditions. In the proposed method, the first sample, oligonucleotide as a ligand, and second sample zones were injected into a capillary with spacers of background solution between the samples and oligonucleotide zones. After applying voltages, only the second sample zone passed through the partially filled oligonucleotide zone, resulting in variations in the peak parameters owing to this interaction. The electropherograms obtained were analyzed using equilibrium, reaction kinetics, and moment theories. In the interaction analyses between small molecules and DNA aptamers, only the small molecules binding to the aptamer showed significant changes in their peak heights and shapes. The estimated kinetic parameters were in good agreement with the reported values, indicating the applicability of the proposed method for drug screening. When interactions between drug candidates and disease-related RNAs were analyzed, one of the candidates showed remarkable variation in the peak parameters upon the addition of potassium ions. Consequently, the proposed method could be one of the ideal assays for drug screening.

Recent developments in capillary and microchip electroseparations of peptides (2019-mid 2021)

The review provides a comprehensive overview of developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, microscale isolation, and physicochemical characterization of peptides from 2019 up to approximately the middle of 2021. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis, such as sample preparation, sorption suppression, EOF control, and detection, are presented. New developments in the individual CE and CEC methods are demonstrated and several types of their applications are shown. They include qualitative and quantitative analysis, determination in complex biomatrices, monitoring of chemical and enzymatic reactions and physicochemical changes, amino acid, sequence, and chiral analyses, and peptide mapping of proteins. In addition, micropreparative separations and determination of significant physicochemical parameters of peptides by CE and CEC methods are described.