Site-selective covalently immobilized alpha 1A adrenergic receptor for thermodynamic and extra-thermodynamic study of four ligands binding to the receptor by chromatographic methods

Preparation of the immobilized α1A-adrenoceptor column by the ultra-high affinity protein pair CL7/Im7 and its application in drug-protein interaction analysis

Immobilizing the target protein on a solid surface with controlled orientation, high specificity, and maintained activity is a proven strategy to enhance the stability of the protein. In this study, we employed an ultra-high affinity protein pair consisting of a mutant of colicin E7 Dnase and its corresponding inhibitor, immunity protein 7(Im7), to develop an immobilized α1A-adrenoceptor (α1A-AR) column. Briefly, we expressed α1A-AR fused with CL7 as a tag at its C-terminus in Escherichia coli cells. Meanwhile, we got His-tagged Im7 at the same manner. Following purification, the His-tagged Im7 was utilized to functionalize the macro-porous silica gel. Leveraging the ultra-high affinity between the protein pair, we achieved robust and specific covalent immobilization of α1A-AR covalently at ambient conditions in buffer solutions, without the requirement for additional regents. The successful immobilization of the receptor, without extraneous protein adsorption, was confirmed through X ray photoelectron spectroscopy and chromatographic investigations. Frontal analysis and adsorption energy distribution analysis further validated the feasibility of the immobilization method. Our findings align well with those reported in the literature. This work is poised to provide a modular platform for conducting effective investigations into the binding interactions between other functional proteins and the drugs.

A strategy for selective screening of dual-target bioactive compounds against hypertrophic scar through inhibiting angiotensin II type 1 receptor while stimulating type 2 receptor from Chinese herbs

BACKGROUND

Cutaneous hypertrophic scar is a fibro-proliferative hard-curing disease. Recent studies have proved that antagonists of angiotensin II type 1 receptor (AT1R) and agonists of type 2 receptor (AT2R) were able to relieve hypertrophic scar. Therefore, establishing new methods to pursue dual-target lead compounds from Chinese herbs is in much demand for treating scar.

METHODS

To this end, we immobilized AT1R or AT2R onto the surface of silica gel from cell lysates through a specific covalent bond by bioorthogonal chemistry. The columns containing immobilized AT1R or AT2R were jointly utilized to pursue potential bioactive compounds simultaneously binding to AT1R and AT2R from the extract of Rhei Radix et Rhizoma. Their functions on AT1R and AT2R expressions were investigated by in vitro and in vivo experiments.

RESULTS

Aloe-emodin and emodin were identified as the potential bioactive compounds binding to both of the two receptors, thereby improving the appearance and pathomorphology of hypertrophic scar. They blocked the AT1R pathway to down-regulate the expression of transforming growth factor-β1 (TGF-β1) and stimulate matrix metalloproteinase-1 (MMP-1) expression. As such, the expression of collagen I/III reduced. Conversely, the bindings of the two compounds to AT2R reduced the production of nuclear factor-кB1 (NF-кB1), whereby the generation of interleukin-6 (IL-6) was blocked.

CONCLUSION

We reasoned that aloe-emodin and emodin had the potential to become dual-target candidates against hypertrophic scar through the regulation of AT1R and AT2R signaling pathways. It showed considerable potential to become a universal strategy for pursuing multi-target bioactive compounds from Chinese herbs by the utilization of diverse immobilized receptors in a desired order.

Discovering the Bioactive Compounds Binding to α1A-Adrenergic Receptor in Guizhi Fuling Formula and Revealing Their Interactions by Immobilizing the Receptor Through Colicin L7 DNase/Immunity Protein 7 Ultra-Affinity System

In this work, Guizhi Fuling Formula (GFF), as well as α1A-adrenergic receptor (α1A-AR) were taken as the research objects. By utilizing the ultra-affinity between Colicin L7 DNase (CL7) and its homologous immune protein 7 (Im7), CL7-tagged α1A-AR was oriented immobilized to the Im7-coated silica gel surface. With the α1A-AR immobilized column in hand, the active compounds in GFF targeted to α1A-AR were screened, and the binding procedures were analyzed. The composite characterization demonstrated that the α1A-AR can be immobilized to the chromatographic stationary phase with good specificity and stability in 3 weeks. Paeoniflorin, cinnamic acid, and paeonol were identified as the active compounds in GFF targeted to α1A-AR. Among them, cinnamic acid and paeonol have the same binding site on α1A-AR as the specific drug tamsulosin. The binding parameters obtained by frontal analysis and injection amount-dependent analysis were consistent in the same concentration range. Collectively, these results indicated that the α1A-AR chromatographic column synthesized by a novel immobilized method was capable of screening and analyzing the functional compounds from the complex matrix, which provided an alternative for rapid screening and analysis to traditional ethnic drugs.

Emerging affinity methods for protein-drug interaction analysis

The study of protein-drug interaction plays a crucial role in understanding drug mechanisms, identifying new drug targets and biomarkers, and facilitating drug development and disease treatment. In recent years, significant progress has been made in various protein-drug interaction research methods due to the rapid development and in-depth application of mass spectrometry, nuclear magnetic resonance, Raman spectroscopy, and other technologies. The progress has enhanced the sensitivity, precision, accuracy, and applicability of analytical methods, enabling the establishment of drug-protein interaction networks. This review discusses various emerging research methods, such as native mass spectrometry, infrared spectroscopy, nuclear magnetic resonance and spectrum, biosensor technologies employing surface enhanced Raman, electrochemistry, and magneto resistive signals, as well as affinity magnetic levitation and affinity chromatography. The article also delves into the principles, applications, advantages, and limitations of these technologies.

Screening and analysis of the targeted compounds in Choerospondias axillaris extract by receptor chromatographic column with immobilized angiotensin II type 1 receptor

As a result of the lack of modern techniques, the study of Tibetan medicine has been hindered in identifying bioactive compounds. Herein, we established a chromatographic approach using an immobilized angiotensin II type 1 receptor (AT1R) via a one-step method triggered by haloalkane dehalogenase. The bioactive compounds from Choerospondias axillaris (Guangzao) were screened and identified using the immobilized AT1R followed by MS. Frontal analysis (FA) and adsorption energy distribution (AED) were used to evaluate the association constants. Molecular docking was used to investigate the binding configurations, and the surface efficiency index, binding efficiency index, and ligand-lipophilicity efficiency (LLE) were calculated to assess the drug-like properties. The results identified naringenin, pinocembrin, and chrysin as the compounds that specifically bind to AT1R in Guangzao. FA and AED confirmed that there is only one type of binding site between these compounds and AT1R. The association constants were (2.40 ± 0.02) × 104 M-1 for naringenin (5.22 ± 0.26) × 104 M-1 for pinocembrin, and (4.27 ± 0.14) × 104 M-1 for chrysin, respectively. These compounds can bind with AT1R through the orthosteric binding pocket. Naringenin exhibited better LLE than pinocembrin and chrysin. These results confirmed the feasibility of using the immobilized AT1R column for screening and analyzing bioactive compounds in Tibetan medicines.

Screening and evaluation of the hit compound from a DNA-encoded library derived from natural products based on immobilized endothelin receptor A

The enormous growing demand for drug candidates binding to endothelin receptor A (ETA) has made it necessary to continuously pursue new strategies for ligand screening and early evaluation. This work achieved the one-step immobilization of ETA based on the bioorthogonal chemistry between the epidermal growth factor receptor tag (EGFR-tag) and ibrutinib. Comprehensive characterizations including Western blot analysis are performed to realize the morphology, antibody/ligand recognition activity, and specificity of the immobilized ETA. Taking macitentan, ambrisentan, and bosentan as an example, we utilized the immobilized ETA to construct a thermodynamic model for the evaluation of the specific ligands binding to ETA. Using this model, we screened the potential compound NP845 from a DNA-encoded library with 10,686 members derived from natural products and calculated the association constant as (2.24 ± 0.15) × 105 M-1 at 37 °C, thereby demonstrating the good pharmacological activity of NP845. The entropy change (∆Sθ), enthalpy change (∆Hθ), and Gibbs free energy (∆Gθ) were 1.75 J/mol·K, -31.1 kJ/mol, and -31.6 kJ/mol at 37 °C, whereby we recognized the electrostatic force was the driving force of the interaction between NP845 and ETA. In vitro cell tests proved that NP845 can downregulate the expression level of PKA, B-Raf, MEK, and ERK1 in VSMC. Our results indicated that NP845 was a potential lead compound for fighting the ailments mediated by ETA.

Multi-target bioactive compound screening from the infructescence of Platycarya strobilacea Sieb. et Zucc. by affinity chromatography using immobilized β2 -adrenoceptor and muscarinic-3 acetylcholine receptor as the stationary phase

As a main source for the recognition and identification of lead compounds, traditional Chinese medicine plays a pivotal role in preventing diseases for years. However, screening bioactive compounds from traditional Chinese medicine remains challenging because of the complexity of the systems and the occurrence of the synergic effect of the compounds. The infructescence of Platycarya strobilacea Sieb. et Zucc is prescribed for allergic rhinitis treatment with unknown bioactive compounds and unclear mechanisms. Herein, we immobilized the β2 -adrenoceptor and muscarine-3 acetylcholine receptor onto the silica gel surface to prepare the stationary phase in a covalent bond through one step. The feasibility of the columns was investigated by the chromatographic method. Ellagic acid and catechin were identified as the bioactive compounds targeting the receptors. The binding constants of ellagic acid were calculated to be (1.56 ± 0.23)×107  M-1 for muscarine-3 acetylcholine receptor and (2.93 ± 0.15)×107  M-1 for β2 -adrenoceptor by frontal analysis. While catechin can bind with muscarine-3 acetylcholine receptor with an affinity of (3.21 ± 0.05)×105  M-1 . Hydrogen bonds and van der Waals' force were the main driving forces for the two compounds with the receptors. The established method provides an alternative for multi-target bioactive compound screening in complex matrices.

Advances in receptor chromatography for drug discovery and drug-receptor interaction studies

Receptor chromatography involves high-throughput separation and accurate drug screening based on specific drug-receptor recognition and affinity, which has been widely used to screen active compounds in complex samples. This review summarizes the immobilization methods for receptors from three aspects: random covalent immobilization methods, site-specific covalent immobilization methods and dual-target receptor chromatography. Meanwhile, it focuses on its applications from three angles: screening active compounds in natural products, in natural-product-derived DNA-encoded compound libraries and drug-receptor interactions. This review provides new insights for the design and application of receptor chromatography, high-throughput and accurate drug screening, drug-receptor interactions and more. Teaser: This review summarizes the immobilization methods of receptors and the application of receptor chromatography, which will provide new insights for the design and application of receptor chromatography, rapid drug screening, drug-receptor interactions and more.

Protein superglue inspired in-situ one-step site-specific immobilization of beta2-adrenoceptor and its application in bioactive compound screening from Cortex Magnoliae Officinalis

The platforms based on immobilization of transmembrane proteins have become an effective way to study drug-protein interaction and identify new leads for drug discovery. Herein, we exploited the protein superglue (i.e. SpyTag-SpyCatcher chemistry) for site-specific, oriented, and in-situ one-step beta2-adrenoceptor (β₂-AR) immobilization. SpyCatcher was used as a fusion tag at the C-terminal of β₂-AR and the macroporous silica gels were functionalized with the SpyTag peptide. Immobilization was realized by immersing the gels into the E.coli cell lysate containing β₂-AR-SpyCatcher. Characterization of the functionalized gels was performed by X-ray photoelectron spectroscopy and fluorescence microscopy. Adsorption energy distribution calculation, injection amount dependent analysis (IADA) and nonlinear chromatographic were used for receptor-ligand interaction analysis. The affinity rank order of four ligands to the receptor was tulobuterol> chlorprenaline> salbutamol> terbutaline, which showed highly consistent with data from the radioligand binding assay and the β₂-AR column prepared by HaloTag technology. Magnolol and honokiol were screened from Cortex Magnoliae Officinalis and proved to promote the expression of the receptor in human airway smooth muscle cells. Our work unraveled the great potential to generate good bioactivity of the immobilized β₂-AR through Spy toolbox. This technology can be extended to the immobilization of other functional proteins, providing a better alternative in the field of bioanalysis, biosensing, and separation science.