Development and characterization of mitochondrial membrane affinity chromatography columns derived from skeletal muscle and platelets for the study of mitochondrial transmembrane proteins

Screening of CPT1A-Targeting Lipid Metabolism Modulators Using Mitochondrial Membrane Chromatography

Carnitine palmitoyltransferase 1A (CPT1A), which resides on the mitochondrial outer membrane, serves as the rate-limiting enzyme of fatty acid β-oxidation. Identifying the compounds targeting CPT1A warrants a promising candidate for modulating lipid metabolism. In this study, we developed a CPT1A-overexpressed mitochondrial membrane chromatography (MMC) to screen the compounds with affinity for CPT1A. Cells overexpressing CPT1A were cultured, and subsequently, their mitochondrial membrane was isolated and immobilized on amino-silica gel cross-linked by glutaraldehyde. After packing the mitochondrial membrane column, retention components of MMC were performed with LC/MS, whose analytic peaks provided structural information on compounds that might interact with mitochondrial membrane proteins. With the newly developed MMC-LC/MS approach, several Chinese traditional medicine extracts, such as Scutellariae Radix and Polygoni Cuspidati Rhizoma et Radix (PCRR), were analyzed. Five noteworthy compounds, baicalin, baicalein, wogonoside, wogonin, and resveratrol, were identified as enhancers of CPT1A enzyme activity, with resveratrol being a new agonist for CPT1A. The study suggests that MMC serves as a reliable screening system for efficiently identifying modulators targeting CPT1A from complex extracts.

Recent advances in screening active components from natural products based on bioaffinity techniques

Natural products have provided numerous lead compounds for drug discovery. However, the traditional analytical methods cannot detect most of these active components, especially at their usual low concentrations, from complex natural products. Herein, we reviewed the recent technological advances (2015–2019) related to the separation and screening bioactive components from natural resources, especially the emerging screening methods based on the bioaffinity techniques, including biological chromatography, affinity electrophoresis, affinity mass spectroscopy, and the latest magnetic and optical methods. These screening methods are uniquely advanced compared to other traditional methods, and they can fish out the active components from complex natural products because of the affinity between target and components, without tedious separation works. Therefore, these new tools can reduce the time and cost of the drug discovery process and accelerate the development of more effective and better-targeted therapeutic agents.

A novel thrombin inhibitory peptide discovered from leech using affinity chromatography combined with ultra-high performance liquid chromatography-high resolution mass spectroscopy

Thrombin (THR) inhibitors play an important role in the treatment of thrombotic diseases. This study established a THR-based bio-specific extraction coupled with affinity chromatography and ultra-high performance liquid chromatography-high resolution mass spectroscopy (UPLC-HR-MS) analysis method to screen and identify THR ligands in Leech. After evaluating the reliability of the screening method using positive control drug (hirudin), it was successfully used to screen the potential active constituents in leech. And a comprehensive analysis of the peptides in leech elution was performed by UPLC-HR-MS, a total of 34 peptides were identified. At the same time, anti-THR activity was explored and inferred by searching databases and published literature. As a result, six peptides were discovered to be potential active compounds in leech. Further, the six peptides were synthesized and in vitro enzymatic activity assay was performed. Finally, SYELPDGQVITIGNER was screened as an anti-THR peptide with an IC50 value of 255.75 µM and it was discovered for the first time from Whitmania pigra Whitman and Hirudo nipponica Whitman. The molecular docking study showed that THR inhibitory activity of the polypeptide was mainly attributed to the hydrogen bond interactions, van der Waals forces and electrostatic interactions interaction between polypeptide and THR. These results suggest that the polypeptide is a potential natural THR inhibitor that can be used as anticoagulant.

Solid-Supported Proteins in the Liquid Chromatography Domain to Probe Ligand-Target Interactions

Ligand-target interactions play a central role in drug discovery processes because these interactions are crucial in biological systems. Small molecules-proteins interactions can regulate and modulate protein function and activity through conformational changes. Therefore, bioanalytical tools to screen new ligands have focused mainly on probing ligand-target interactions. These interactions have been evaluated by using solid-supported proteins, which provide advantages like increased protein stability and easier protein extraction from the reaction medium, which enables protein reuse. In some specific approaches, precisely in the ligand fishing assay, the bioanalytical method allows the ligands to be directly isolated from complex mixtures, including combinatorial libraries and natural products extracts without prior purification or fractionation steps. Most of these screening assays are based on liquid chromatography separation, and the binding events can be monitored through on-line or off-line methods. In the on-line approaches, solid supports containing the immobilized biological target are used as chromatographic columns most of the time. Several terms have been used to refer to such approaches, such as weak affinity chromatography, high-performance affinity chromatography, on-flow activity assays, and high-performance liquid affinity chromatography. On the other hand, in the off-line approaches, the binding event occurs outside the liquid chromatography system and may encompass affinity and activity-based assays in which the biological target is immobilized on magnetic particles or monolithic silica, among others. After the incubation step, the supernatant or the eluate from the binding assay is analyzed by liquid chromatography coupled to various detectors. Regardless of the selected bioanalytical approach, the use of solid supported proteins has significantly contributed to the development of automated and reliable screening methods that enable ligands to be isolated and characterized in complex matrixes without purification, thereby reducing costs and avoiding time-laborious steps. This review provides a critical overview of recently developed assays.

Cell-membrane coated iron oxide nanoparticles for isolation and specific identification of drug leads from complex matrices

The lack of suitable tools for the identification of potential drug leads from complex matrices is a bottleneck in drug discovery. Here, we report a novel method to screen complex matrices for new drug leads targeting transmembrane receptors. Using α3β4 nicotinic receptors as a model system, we successfully demonstrated the ability of this new tool for the specific identification and effective extraction of binding compounds from complex mixtures. The formation of cell-membrane coated nanoparticles was confirmed by transmission electron microscopy. In particular, we have developed a direct tool to evaluate the presence of functional α3β4 nicotinic receptors on the cell membrane. The specific ligand binding to α3β4 nicotinic receptors was examined through ligand fishing experiments and confirmed by high-performance liquid chromatography coupled with diode-array detection and electrospray ionization mass spectrometry. This tool has a great potential to transform the drug discovery process focusing on identification of compounds targeting transmembrane proteins, as more than 50% of all modern pharmaceuticals use membrane proteins as prime targets.