1
|
Sharmeen S, Woolfork AG, Hage DS. Generation of affinity maps for thiazolidinediones with human serum albumin using affinity microcolumns. II. Effects of advanced glycation end products on multisite drug binding. J Chromatogr B Analyt Technol Biomed Life Sci 2024; 1247:124333. [PMID: 39395238 DOI: 10.1016/j.jchromb.2024.124333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Revised: 09/29/2024] [Accepted: 10/01/2024] [Indexed: 10/14/2024]
Abstract
Multisite protein interactions by the thiazolidinedione-class drugs pioglitazone and rosiglitazone were examined by using high-performance affinity microcolumns that contained normal human serum albumin (HSA) vs HSA that had been modified to form advanced glycation end products by glyoxal (Go) or methylglyoxal (MGo). The results were used to generate an affinity map for these drugs at several key regions on HSA. Strong binding (∼105 M-1) by these drugs was seen at both Sudlow sites I and II. About a 50 % decrease in the affinities at Sudlow site II was observed for pioglitazone for Go-modified HSA, while either a 47 % decrease or 1.6-fold increase in affinity was seen for MGo-modified HSA, depending on the extent of modification. The binding affinity for rosiglitazone at Sudlow site II had a 40-83 % decrease for Go-modified HSA and either a non-significant change or 1.4-fold increase for MGo-modified HSA. At Sudlow site I, pioglitazone gave a 41 % decrease in affinity for either Go or MGo-modified HSA, and for rosiglitazone up to a 55 % decrease or 1.3-fold increase in affinity was noted. Positive allosteric effects were seen by these drugs with the tamoxifen site of HSA, and neither drug had any notable binding at the digitoxin site for the normal or modified forms of HSA. Rosiglitazone also had weak interactions at a site in subdomain IB, which increased in affinity by up to 5.0-fold with the Go- or MGo-modified HSA. This study illustrated how affinity microcolumns can be used to provide a detailed analysis of solute-protein systems that involve complex interactions. The data obtained should also be valuable in providing a better understanding of how drug interactions with HSA and other proteins can be altered by modifications of these binding agents in diseases such as diabetes.
Collapse
Affiliation(s)
- Sadia Sharmeen
- Department of Chemistry, University of Nebraska-Lincoln, USA
| | | | - David S Hage
- Department of Chemistry, University of Nebraska-Lincoln, USA.
| |
Collapse
|
2
|
Sharmeen S, Woolfork A, Hage DS. Generation of affinity maps for thiazolidinediones with human serum albumin using affinity microcolumns. I. Studies of effects by glycation on multisite drug binding. J Chromatogr B Analyt Technol Biomed Life Sci 2024; 1236:124070. [PMID: 38460447 DOI: 10.1016/j.jchromb.2024.124070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 02/09/2024] [Accepted: 02/27/2024] [Indexed: 03/11/2024]
Abstract
Human serum albumin (HSA) is known to undergo modifications by glucose during diabetes. This process produces glycated HSA that can have altered binding to some drugs. In this study, high-performance affinity microcolumns and competition studies were used to see how glycation affects the binding by two thiazolidinedione-class drugs (i.e., pioglitazone and rosiglitazone) at specific regions of HSA. These regions included Sudlow sites I and II, the tamoxifen and digitoxin sites, and a drug-binding site located in subdomain IB. At Sudlow site II, the association equilibrium constants (or binding constants) for pioglitazone and rosiglitazone with normal HSA were 1.7 × 105 M-1 and 2.0 × 105 M-1 at pH 7.4 and 37 °C, with values that changed by up to 5.7-fold for glycated HSA. Sudlow site I of normal HSA had binding constants for pioglitazone and rosiglitazone of 3.4 × 105 M-1 and 4.6 × 105 M-1, with these values changing by up to 1.5-fold for glycated HSA. Rosiglitazone was found to also bind a second region that had a positive allosteric effect on Sudlow site I for all the tested preparations of HSA (binding affinity, 1.1-3.2 × 105 M-1; coupling constant for Sudlow site I, 1.20-1.34). Both drugs had a strong positive allosteric effect on the tamoxifen site of HSA (coupling constants, 13.7-19.9 for pioglitazone and 3.7-11.5 for rosiglitazone). Rosiglitazone also had weak interactions at a site in subdomain IB, with a binding constant of 1.4 × 103 M-1 for normal HSA and a value that was altered by up to 6.8-fold with glycated HSA. Neither of the tested drugs had any significant binding at the digitoxin site. The results were used to produce affinity maps that described binding by these thiazolidinediones with HSA and the effects of glycation on these interactions during diabetes.
Collapse
Affiliation(s)
- Sadia Sharmeen
- Department of Chemistry, University of Nebraska-Lincoln, USA
| | - Ashley Woolfork
- Department of Chemistry, University of Nebraska-Lincoln, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska-Lincoln, USA.
| |
Collapse
|
3
|
Guillaume YC, André C. Immobilization of the SARS-CoV-2-receptor binding domain onto methacrylate-based monoliths for nano LC at 30 nL min -1 and application for research of its ligands. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:156-164. [PMID: 34927183 DOI: 10.1039/d1ay01913a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
For the design of novel potent molecules against therapeutic protein targets produced in a low quantity or that are very expensive, the development of miniaturized analytical techniques is of crucial importance. One challenging target is the receptor binding domain (RBD) of the SARS-CoV-2-spike protein (S), which mediates the binding of the virus to host cells. In the present study, the RBD protein was thus immobilized on polymethacrylate monoliths prepared in a miniaturized capillary column (25 μm internal diameter; 70 mm length) by in situ polymerization, which could offer low backpressure in Nano LC at 30 nL min-1. The immobilized quantity of the expensive RBD protein on the organic monolith was very low, in the submicrogram range, i.e., 0.060 μg. The immobilization method reduced non-selective interactions between the ligand and the organic monolith matrix and maintained the functionality of RBD due to the high activity rate (96%). The performance of this miniaturized affinity capillary column was demonstrated for the rapid evaluation of a recognition assay induced by 1,2,3,4,6-pentagalloyl glucose (PGG), a known ligand of RBD, and by five other molecules. In addition, it was demonstrated that competitive experiments could be performed with our miniaturized system to reveal the existence of only one type of binding site for three ligands of RBD, namely carbenoxolone, simeprevir and irinotecan. All these results showed the potential of our analytical miniaturized affinity system for the determination of interactions between potential ligands and immobilized RBD of SARS-CoV-2 to aid in the battle against COVID-19.
Collapse
Affiliation(s)
- Yves Claude Guillaume
- Univ Franche - Comté, EA481 Neurosciences Intégratives et Cliniques/Pôle Chimie Analytique Bioanalytique et Physique (PCABP), F-25000 Besançon, France.
| | - Claire André
- Univ Franche - Comté, EA481 Neurosciences Intégratives et Cliniques/Pôle Chimie Analytique Bioanalytique et Physique (PCABP), F-25000 Besançon, France.
- CHRU Besançon, Pôle Pharmaceutique, F-25000 Besançon, France
| |
Collapse
|
4
|
Enantioresolution and Binding Affinity Studies on Human Serum Albumin: Recent Applications and Trends. CHEMOSENSORS 2021. [DOI: 10.3390/chemosensors9110304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interaction between proteins and drugs or other bioactive compounds has been widely explored over the past years. Several methods for analysis of this phenomenon have been developed and improved. Nowadays, increasing attention is paid to innovative methods, such as high performance affinity liquid chromatography (HPALC) and affinity capillary electrophoresis (ACE), taking into account various advantages. Moreover, the development of separation methods for the analysis and resolution of chiral drugs has been an area of ongoing interest in analytical and medicinal chemistry research. In addition to bioaffinity binding studies, both HPALC and ACE al-low one to perform other type of analyses, namely, displacement studies and enantioseparation of racemic or enantiomeric mixtures. Actually, proteins used as chiral selectors in chromatographic and electrophoretic methods have unique enantioselective properties demonstrating suitability for the enantioseparation of a large variety of chiral drugs or other bioactive compounds. This review is mainly focused in chromatographic and electrophoretic methods using human serum albumin (HSA), the most abundant plasma protein, as chiral selector for binding affinity analysis and enantioresolution of drugs. For both analytical purposes, updated examples are presented to highlight recent applications and current trends.
Collapse
|
5
|
Nevídalová H, Michalcová L, Glatz Z. Capillary electrophoresis-based immunoassay and aptamer assay: A review. Electrophoresis 2020; 41:414-433. [PMID: 31975407 DOI: 10.1002/elps.201900426] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 12/31/2022]
Abstract
Over the last two decades, the group of techniques called affinity probe CE has been widely used for the detection and the determination of several types of biomolecules with high sensitivity. These techniques combine the low sample consumption and high separation power of CE with the selectivity of the probe to the target molecule. The assays can be defined according to the type of probe used: CE immunoassays, with an antibody as the probe, or aptamer-based CE, with an aptamer as the probe. Immunoassays are generally divided into homogeneous and heterogeneous groups, and homogeneous variant can be further performed in competitive or noncompetitive formats. Interacting partners are free in solution at homogeneous assay, as opposed to heterogeneous analyses, where one of them is immobilized onto a solid support. Highly sensitive fluorescence, chemiluminescence or electrochemical detections were typically used in this type of study. The use of the aptamers as probes has several advantages over antibodies such as shorter generation time, higher thermal stability, lower price, and lower variability. The aptamer-based CE technique was in practice utilized for the determination of proteins in biological fluids and environmentally or clinically important small molecules. Both techniques were also transferred to microchip. This review is focused on theoretical principles of these techniques and a summary of their applications in research.
Collapse
Affiliation(s)
- Hana Nevídalová
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Lenka Michalcová
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Zdeněk Glatz
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| |
Collapse
|
6
|
Monolith weak affinity chromatography for μg-protein-ligand interaction study. J Pharm Biomed Anal 2019; 166:164-173. [DOI: 10.1016/j.jpba.2019.01.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 11/17/2022]
|
7
|
Tao P, Li Z, Woolfork AG, Hage DS. Characterization of tolazamide binding with glycated and normal human serum albumin by using high-performance affinity chromatography. J Pharm Biomed Anal 2019; 166:273-280. [PMID: 30682693 DOI: 10.1016/j.jpba.2019.01.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/05/2019] [Accepted: 01/13/2019] [Indexed: 12/16/2022]
Abstract
Sulfonylurea drugs are antidiabetic drugs that are utilized in the treatment of type II diabetes and often have significant binding with human serum albumin (HSA). Immobilized samples of normal or glycated HSA in affinity microcolumns were used to investigate interactions of these proteins with the sulfonylurea drug tolazamide. HPLC and frontal analysis were used to first examine the overall binding of this drug with these samples of HSA. It was found that tolazamide had two general classes of binding sites (i.e., high and low affinity) for normal and glycated HSA. The higher affinity sites had binding constants of around 4.3-6.0 × 104 M-1 for these interactions at pH 7.4 and 37 °C, while the lower affinity sites had binding strengths of 4.9-9.1 × 103 M-1. Zonal competition studies between tolazamide and probes for Sudlow sites I and II on HSA were also performed and used to provide site-specific affinities for tolazamide at these sites. A decrease of 22% in affinity was observed for tolazamide at Sudlow site I and an increase up to 58% was seen at Sudlow site II when comparing glycated HSA with normal HSA. These observed changes were compared to those of other first-generation sulfonylurea drugs, providing information on how glycation can alter the total and local binding strength of tolazamide and related compounds with HSA under levels of glycation seen in patients with diabetes.
Collapse
Affiliation(s)
- Pingyang Tao
- Chemistry Department, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Zhao Li
- Chemistry Department, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Ashley G Woolfork
- Chemistry Department, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - David S Hage
- Chemistry Department, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
| |
Collapse
|
8
|
Nevídalová H, Michalcová L, Glatz Z. Capillary electrophoresis-based approaches for the study of affinity interactions combined with various sensitive and nontraditional detection techniques. Electrophoresis 2019; 40:625-642. [PMID: 30600537 DOI: 10.1002/elps.201800367] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/20/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022]
Abstract
Nearly all processes in living organisms are controlled and regulated by the synergy of many biomolecule interactions involving proteins, peptides, nucleic acids, nucleotides, saccharides, and small molecular weight ligands. There is growing interest in understanding them, not only for the purposes of interactomics as an essential part of system biology, but also in their further elucidation in disease pathology, diagnostics, and treatment. The necessity of detailed investigation of these interactions leads to the requirement of laboratory methods characterized by high efficiency and sensitivity. As a result, many instrumental approaches differing in their fundamental principles have been developed, including those based on capillary electrophoresis. Although capillary electrophoresis offers numerous advantages for such studies, it still has one serious limitation, its poor concentration sensitivity with the most commonly used detection method-ultraviolet-visible spectrometry. However, coupling capillary electrophoresis with a more sensitive detector fulfils the above-mentioned requirement. In this review, capillary electrophoresis combined with fluorescence, mass spectrometry, and several nontraditional detection techniques in affinity interaction studies are summarized and discussed, together with the possibility of conducting these measurements in microchip format.
Collapse
Affiliation(s)
- Hana Nevídalová
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Lenka Michalcová
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Zdeněk Glatz
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| |
Collapse
|
9
|
Tao P, Li Z, Matsuda R, Hage DS. Chromatographic studies of chlorpropamide interactions with normal and glycated human serum albumin based on affinity microcolumns. J Chromatogr B Analyt Technol Biomed Life Sci 2018; 1097-1098:64-73. [PMID: 30205233 DOI: 10.1016/j.jchromb.2018.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/30/2018] [Accepted: 09/01/2018] [Indexed: 01/02/2023]
Abstract
Sulfonylurea drugs have significant binding to proteins in blood, with most of this binding believed to occur with human serum albumin (HSA). High performance affinity chromatography and affinity microcolumns containing immobilized HSA were used to investigate binding by the sulfonylurea drug chlorpropamide to normal HSA and glycated HSA, which is a modified form of HSA that has an increased serum concentration in diabetes. Experiments employing frontal analysis indicated that the binding by chlorpropamide gave a good fit to a two-site model for both normal HSA and glycated HSA samples that were representative of controlled or advanced diabetes. These interactions involved a set of moderate-to-high affinity sites and a set of lower affinity sites, with binding constants in the range of 6.2-9.9 × 104 M-1 and 0.18-0.57 × 104 M-1, respectively, at pH 7.4 and 37 °C. Competition studies utilizing a zonal elution format demonstrated that chlorpropamide could interact at both Sudlow sites I and II of HSA, with affinities in the range expected for the moderate-to-high affinity sites of this drug. The affinity of chlorpropamide at Sudlow site I had a small increase of up to 1.2-fold when comparing the normal HSA and glycated HSA samples. Chlorpropamide gave a larger 1.4- to over 1.5-fold increase at Sudlow site II when the affinity of this drug was compared between normal HSA and the same samples of glycated HSA. These results were compared to those obtained previously with other sulfonylurea drugs to help determine how glycation can change the overall and site-selective binding strength of these drugs with HSA at levels of protein modification that are seen in patients with diabetes.
Collapse
Affiliation(s)
- Pingyang Tao
- Chemistry Department, University of Nebraska, Lincoln, NE 68588, USA
| | - Zhao Li
- Chemistry Department, University of Nebraska, Lincoln, NE 68588, USA
| | - Ryan Matsuda
- Chemistry Department, University of Nebraska, Lincoln, NE 68588, USA
| | - David S Hage
- Chemistry Department, University of Nebraska, Lincoln, NE 68588, USA.
| |
Collapse
|
10
|
Beeram SR, Zheng X, Suh K, Hage DS. Characterization of solution-phase drug-protein interactions by ultrafast affinity extraction. Methods 2018; 146:46-57. [PMID: 29510250 DOI: 10.1016/j.ymeth.2018.02.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/17/2018] [Accepted: 02/22/2018] [Indexed: 11/25/2022] Open
Abstract
A number of tools based on high-performance affinity separations have been developed for studying drug-protein interactions. An example of one recent approach is ultrafast affinity extraction. This method has been employed to examine the free (or non-bound) fractions of drugs and other solutes in simple or complex samples that contain soluble binding agents. These free fractions have also been used to determine the binding constants and rate constants for the interactions of drugs with these soluble agents. This report describes the general principles of ultrafast affinity extraction and the experimental conditions under which it can be used to characterize such interactions. This method will be illustrated by utilizing data that have been obtained when using this approach to measure the binding and dissociation of various drugs with the serum transport proteins human serum albumin and alpha1-acid glycoprotein. A number of practical factors will be discussed that should be considered in the design and optimization of this approach for use with single-column or multi-column systems. Techniques will also be described for analyzing the resulting data for the determination of free fractions, rate constants and binding constants. In addition, the extension of this method to complex samples, such as clinical specimens, will be considered.
Collapse
Affiliation(s)
- Sandya R Beeram
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Xiwei Zheng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Kyungah Suh
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| |
Collapse
|
11
|
Kelly JM, Amor-Coarasa A, Nikolopoulou A, Wüstemann T, Barelli P, Kim D, Williams C, Zheng X, Bi C, Hu B, Warren JD, Hage DS, DiMagno SG, Babich JW. Dual-Target Binding Ligands with Modulated Pharmacokinetics for Endoradiotherapy of Prostate Cancer. J Nucl Med 2017; 58:1442-1449. [DOI: 10.2967/jnumed.116.188722] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/11/2017] [Indexed: 01/05/2023] Open
|
12
|
Li Z, Beeram SR, Bi C, Suresh D, Zheng X, Hage DS. High-Performance Affinity Chromatography: Applications in Drug-Protein Binding Studies and Personalized Medicine. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 102:1-39. [PMID: 26827600 DOI: 10.1016/bs.apcsb.2015.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The binding of drugs with proteins and other agents in serum is of interest in personalized medicine because this process can affect the dosage and action of drugs. The extent of this binding may also vary with a given disease state. These interactions may involve serum proteins, such as human serum albumin or α1-acid glycoprotein, or other agents, such as lipoproteins. High-performance affinity chromatography (HPAC) is a tool that has received increasing interest as a means for studying these interactions. This review discusses the general principles of HPAC and the various approaches that have been used in this technique to examine drug-protein binding and in work related to personalized medicine. These approaches include frontal analysis and zonal elution, as well as peak decay analysis, ultrafast affinity extraction, and chromatographic immunoassays. The operation of each method is described and examples of applications for these techniques are provided. The type of information that can be obtained by these methods is also discussed, as related to the analysis of drug-protein binding and the study of clinical or pharmaceutical samples.
Collapse
Affiliation(s)
- Zhao Li
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Sandya R Beeram
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Cong Bi
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - D Suresh
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Xiwei Zheng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
| |
Collapse
|
13
|
Analysis of multi-site drug-protein interactions by high-performance affinity chromatography: Binding by glimepiride to normal or glycated human serum albumin. J Chromatogr A 2015; 1408:133-44. [PMID: 26189669 DOI: 10.1016/j.chroma.2015.07.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 06/29/2015] [Accepted: 07/03/2015] [Indexed: 11/22/2022]
Abstract
High-performance affinity chromatography (HPAC) was used in a variety of formats to examine multi-site interactions between glimepiride, a third-generation sulfonylurea drug, and normal or in vitro glycated forms of the transport protein human serum albumin (HSA). Frontal analysis revealed that glimepiride interacts with normal HSA and glycated HSA at a group of high affinity sites (association equilibrium constant, or Ka, 9.2-11.8×10(5)M(-1) at pH 7.4 and 37°C) and a group of lower affinity regions (Ka, 5.9-16×10(3)M(-1)). Zonal elution competition studies were designed and carried out in both normal- and reversed-role formats to investigate the binding by this drug at specific sites. These experiments indicated that glimepiride was interacting at both Sudlow sites I and II. Allosteric effects were also noted with R-warfarin at Sudlow site I and with tamoxifen at the tamoxifen site on HSA. The binding at Sudlow site I had a 2.1- to 2.3-fold increase in affinity in going from normal HSA to the glycated samples of HSA. There was no significant change in the affinity for glimepiride at Sudlow site II in going from normal HSA to a moderately glycated sample of HSA, but a slight decrease in affinity was seen in going to a more highly glycated HSA sample. These results demonstrated how various HPAC-based methods can be used to profile and characterize multi-site binding by a drug such as glimepiride to a protein and its modified forms. The information obtained from this study should be useful in providing a better understanding of how drug-protein binding may be affected by glycation and of how separation and analysis methods based on HPAC can be employed to study systems with complex interactions or that involve modified proteins.
Collapse
|
14
|
Zheng X, Podariu M, Bi C, Hage DS. Development of enhanced capacity affinity microcolumns by using a hybrid of protein cross-linking/modification and immobilization. J Chromatogr A 2015; 1400:82-90. [PMID: 25981291 DOI: 10.1016/j.chroma.2015.04.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 11/29/2022]
Abstract
A hybrid method was examined for increasing the binding capacity and activity of protein-based affinity columns by using a combination of protein cross-linking/modification and covalent immobilization. Various applications of this approach in the study of drug-protein interactions and in use with affinity microcolumns were considered. Human serum albumin (HSA) was utilized as a model protein for this work. Bismaleimidohexane (BMH, a homobifunctional maleimide) was used to modify and/or cross-link HSA through the single free sulfhydryl group that is present on this protein. Up to a 75-113% increase in protein content was obtained when comparing affinity supports that were prepared with BMH versus reference supports that were made by using only covalent immobilization. Several drugs that are known to bind HSA (e.g., warfarin, verapamil and carbamazepine) were further found to have a significant increase in retention on HSA microcolumns that were treated with BMH (i.e., a 70-100% increase in protein-based retention). These BMH-treated HSA microcolumns were used in chiral separations and in ultrafast affinity extraction to measure free drug fractions in drug/protein mixtures, with the latter method giving association equilibrium constants that had good agreement with literature values. In addition, it was found that the reversible binding of HSA with ethacrynic acid, an agent that can combine irreversibly with the free sulfhydryl group on this protein, could be examined by using the BMH-treated HSA microcolumns. The same hybrid immobilization method could be extended to other proteins or alternative applications that may require protein-based affinity columns with enhanced binding capacities and activities.
Collapse
Affiliation(s)
- Xiwei Zheng
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - Maria Podariu
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - Cong Bi
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA.
| |
Collapse
|