Determination of Binding Constants for Basic Drugs with Serum Albumin by Affinity Capillary Electrophoresis with the Partial Filling Technique

Analysis of drug interactions with serum proteins and related binding agents by affinity capillary electrophoresis: A review

Biomolecules such as serum proteins can interact with drugs in the body and influence their pharmaceutical effects. Specific and precise methods that analyze these interactions are critical for drug development or monitoring and for diagnostic purposes. Affinity capillary electrophoresis (ACE) is one technique that can be used to examine the binding between drugs and serum proteins, or other agents found in serum or blood. This article will review the basic principles of ACE, along with related affinity-based capillary electrophoresis (CE) methods, and examine recent developments that have occurred in this field as related to the characterization of drug-protein interactions. An overview will be given of the various formats that can be used in ACE and CE for such work, including the relative advantages or weaknesses of each approach. Various applications of ACE and affinity-based CE methods for the analysis of drug interactions with serum proteins and other binding agents will also be presented. Applications of ACE and related techniques that will be discussed include drug interaction studies with serum agents, chiral drug separations employing serum proteins, and the use of CE in hybrid methods to characterize drug binding with serum proteins.

Affinity capillary electrophoresis for studying interactions in life sciences

Affinity capillary electrophoresis (ACE) analyzes noncovalent interactions between ligands and analytes based on changes in their electrophoretic mobility. This technique has been widely used to investigate various biomolecules, mainly proteins, polysaccharides and hormones. ACE is becoming a technique of choice to validate high throughput screening results, since it is very predictively working in realistic and relevant media, e.g. in body fluids. It is highly recommended to incorporate ACE as a powerful analytical tool to properly prepare animal testing and preclinical studies. The interacting molecules can be found free in solution or can be immobilized to a solid support. Thus, ACE is classified in two modes, free solution ACE and immobilized ACE. Every ACE mode has advantages and disadvantages. Each can be used for a variety of applications. This review covers literature of scopus and SciFinder data base in the period from 2016 until beginning 2018, including the keywords "affinity capillary electrophoresis", "immunoaffinity capillary electrophoresis", "immunoassay capillary electrophoresis" and "immunosorbent capillary electrophoresis". More than 200 articles have been found and 112 have been selected and thoroughly discussed. During this period, the data processing and the underlying calculations in mobility shift ACE (ms ACE), frontal analysis ACE (FA ACE) and plug-plug kinetic capillary electrophoresis (ppKCE) as mostly applied free solution techniques have substantially improved. The range of applications in diverse free solution and immobilized ACE techniques has been considerably broadened.

Interaction of human serum albumin with uremic toxins: a thermodynamic study

Interaction of uremic toxins with HSA is studied by ITC and understood in terms of thermodynamic driving forces.

Molecular modeling and multi-spectroscopic approaches to study the interaction between antibacterial drug and human immunoglobulin G

Mechanistic and conformational studies on the interaction of sulfamethoxazole (SMX) with human immunoglobulin G (HIgG) were performed by molecular modeling and multi-spectroscopic methods. The interaction mechanism was firstly predicted through molecular modeling that confirmed the interaction between SMX and HIgG. The binding parameters and thermodynamic parameters at different temperatures had been calculated according to the Stern-Volmer, Scatchard, Sips and Van 't Hoff equations, respectively. Experimental results showed that the fluorescence intensity of HIgG was quenched by the gradual addition of SMX. The binding constants of SMX with HIgG decreased with the increase of temperature, which meant that the quenching mechanism was a static quenching. Meanwhile, the results also confirmed that there was one independent class of binding site on HIgG for SMX during their interaction. The thermodynamic parameters of the reaction, namely standard enthalpy ΔH(0) and entropy ΔS(0), had been calculated to be -14.69 kJ·mol(-1) and 22.99 J·mol(-1) ·K(-1), respectively, which suggested that the electrostatic and hydrophobic interactions were the predominant intermolecular forces in stabilizing the SMX-HIgG complex. Furthermore, experimental results obtained from three-dimensional fluorescence spectroscopy, UV-vis absorption spectroscopy and circular dichroism (CD) spectroscopy confirmed that the conformational structure of HIgG was altered in the presence of SMX.

Frontal analysis in microchip CE: a simple and accurate method for determination of protein-DNA dissociation constant

Equilibrium constants, such as the dissociation constant (K(d)), are a key measurement of noncovalent interactions that are of importance for the proper functioning of molecules in living systems. Frontal analysis (FA) is a simple and accurate CE method for the determination of K(d). Microchip CE coupled with LIF detection was used to determine K(d) of protein-DNA interactions using the FA method. A model system of IgE and the IgE-binding aptamer was selected to demonstrate the capability of FA in microchip CE. Because the fluorescence emission was dependent on the dye migration velocity, the velocity of the free aptamer was adjusted to be the same as that of the aptamer-IgE complex by setting up individual separation voltage configurations for the free and bound aptamers. The ratio of the free and bound aptamers in the equilibrium mixture was directly measured from the heights of their plateaus detected at 1.0 cm from the intersection of the microchip, and no internal standard was needed. The K(d) of the IgE-aptamer pair was determined as 6 +/- 2 nM which is consistent with the reported results (8 nM).