Ligand binding

An emerging drug design method is based on the secondary binding site effect, where small molecule drugs are designed to bind to secondary binding sites on target biomolecules rather than primary orthomorphic sites. Successful potential drugs (known as allosteric modulators) will be able to bind to allosteric sites and remotely alter (or modify) the conformation of the main orthosteric binding sites of biological targets. Allosteric modulators (AMs) are ligands of proteins that act through binding sites different from natural (orthosteric) ligand sites. AMs are relatively small, more lipophilic, and more rigid compounds. The binding efficacy of AMs with their targets is often slightly lower. AMs are divided into positive AMs (PAMs) and negative AMs (NAMs). AMs are ideal drug targets because they can fine-tune receptor activity while preserving the spatial and temporal signal transduction characteristics of endogenous ligands, resulting in fewer targeted side effects, improved subtype selectivity, and better promotion of biased signal transduction than normal ligands.

MCE designs a unique collection of 223 small allosteric modulators. It is a good tool to be used for research on metabolize, cancer and other diseases.

Neurotransmitter (NT) receptors, also known as neuroreceptors, are a broadly diverse group of membrane proteins that bind neurotransmitters for neuronal signaling. There are two major types of neurotransmitter receptors: ionotropic and metabotropic. Ionotropic receptors are ligand-gated ion channels, meaning that the receptor protein includes both a neurotransmitter binding site and an ion channel. The binding of a neurotransmitter molecule (the ligand) to the binding site induces a conformational change in the receptor structure, which opens, or gates, the ion channel. The term “metabotropic receptors” is typically used to refer to transmembrane G-protein-coupled receptors. Metabotropic receptors trigger second messenger-mediated effects within cells after neurotransmitter binding.

In some neurological diseases, the neurotransmitter receptor itself appears to be the target of the disease process. Many neuroactive drugs act by modifying neurotransmitter receptors. A better understanding of neurotransmitter receptor changes in disease may lead to improvements in therapy.

MCE designs a unique collection of 2,276 compounds targeting a variety of neurotransmitter receptors. MCE Neurotransmitter Receptor Compound Library is a useful tool for neurological diseases drug discovery.

Proteolysis-targeting chimera (PROTAC) has been developed to be a useful technology for targeted protein degradation. PROTACs consist of a ligand for E3 ligase (E3 ligase binder), a linker and a ligand (mostly small-molecule inhibitor) for protein of interest（target binder）. Upon binding to the target protein, the PROTACs can recruit E3 for target protein ubiquitination, which is subjected to proteasome-mediated degradation.

Although there are more than 600 E3 ubiquitin ligases, only several with small molecule ligands have been used for designing PROTACs, including Skp1-Cullin-F box complex containing Hrt1 (SCF), Von Hippel-Lindau tumor suppressor (VHL), Cereblon (CRBN), inhibitor of apoptosis proteins (IAPs), and mouse double minute 2 homolog (MDM2).

MCE carefully prepared a unique collection of 96 ligands for E3 ligase, which have been reported to be used in PROTAC design. MCE E3 ligase ligand library is a useful tool for PROTAC development.

Proteolysis-targeting chimera (PROTAC) has been developed to be a useful technology for targeted protein degradation. PROTACs consist of a ligand for E3 ligase (E3 ligase binder), a linker and a ligand (mostly small-molecule inhibitor) for protein of interest（target binder）. Upon binding to the target protein, the PROTACs can recruit E3 for target protein ubiquitination, which is subjected to proteasome-mediated degradation. Therefore, PROTACs execute their functions by degrading the target proteins rather than inhibiting them, which has a great superiority in overcoming resistance caused by target mutation or overexpression. To date, PROTAC technology has been applied to a variety of targets, including AR, ER, BTK, BET, and BCR-ABL to overcome resistance.

MCE carefully prepared a unique collection of 69 ligands for target proteins, which have been reported to be used in PROTAC design. MCE Target Protein Ligand Library is a useful tool for PROTAC development.

Sodium channels conduct sodium ions (Na+) through a cell's plasma membrane that are the source of excitatory currents for the nervous system and muscle. Na channels are classified according to the trigger that opens the channel for such ions, i.e. either a voltage-change (Voltage-gated, voltage-sensitive, or voltage-dependent sodium channel also called VGSCs or Nav channel) or a binding of a substance (a ligand) to the channel (ligand-gated sodium channels). Dysfunction in voltage-gated sodium channels correlates with neurological and cardiac diseases, including epilepsy, myopathies, pain and cardiac arrhythmias. Sodium channel blockers are used in the treatment of cardiac arrhythmia, pain and convulsion.

MCE offers a unique collection of 171 sodium channel blocker and antagonists, all of which have the identified inhibitory effect on sodium channels. MCE Sodium Channel Blocker Library can be used for neurological and cardiac diseases drug discovery and sodium channel research.

19F-NMR has proved to be a detection mode in fragment-based drug discovery (FBDD) for studies of protein structure and interactions. 19F shows high sensitivity for NMR detection, and the exquisite sensitivity of 19F chemical shifts and linewidths to ligand binding all make it a valuable approach in FBDD.F (Fluorine) -Fragments can be used for 19F-NMR detection after binding to target proteins, and can be used as an effective 19F-NMR tool for FBDD.

MCE designs a unique collection of 5,105 F-fragments, all of which obey a heuristic rule called the “Rule of Three (RO3)”, in which molecular weight ≤300 Da, the number of hydrogen bond donors (H-donors) ≤3, the number of hydrogen bond acceptors (H-acceptors) is ≤3 and cLogP is ≤3. This F-fragments library is an important source of lead-like drugs.

Membrane receptors, also known cell surface receptors or transmembrane receptors, are transmembrane proteins embedded into the plasma membrane which play an essential role in maintaining communication between the internal processes within the cell and various types of extracellular signals. They act in cell signaling by receiving (binding to) extracellular molecules, which are also called ligands. These extracellular molecules include hormones, cytokines, growth factors, neurotransmitters, lipophilic signaling molecules such as prostaglandins, and cell recognition molecules.

There are three kinds of membrane receptors: ion channel-linked receptors, enzyme-linked receptors and G-protein-linked receptors. They play important roles in keeping human normal physiologic processes. GPCRs and ion channels are important drug targets in drug discovery.

MCE provides a unique collection of 6,168 compounds targeting a variety of membrane receptors. MCE Membrane reeptor-targeted Compound Library can be used for membrane receptor-focused screening and drug discovery.

Protein tyrosine kinases (PTKs) are key signaling molecules and important drug targets. Two classes of PTKs are present in cells: the transmembrane receptor PTKs (RTKs) and the nonreceptor PTKs. The RTK family includes the receptors for insulin and for many growth factors, such as EGFR, FGFR, PDGFR, VEGFR, and NGFR. RTKs are transmembrane glycoproteins that are activated by the binding of their ligands, and they transduce the extracellular signal to the cytoplasm by phosphorylating tyrosine residues on the receptors themselves (autophosphorylation) and on downstream signaling proteins. Their principal functions of PTKs involve the regulation of multicellular aspects of the organism. Cell to cell signals concerning growth, differentiation, adhesion, motility, and death are frequently transmitted through tyrosine kinases. In humans, tyrosine kinases have been demonstrated to play significant roles in the development of many disease states, including diabetes and cancers.

MCE designs a unique collection of 1,414 compounds that act as a useful tool for PTKs-related drug screening and disease research.

Ion channel is a membrane-binding enzyme whose catalytic site is an ion conduction pore, which is opened and closed in response to specific environmental stimuli (voltage, ligand concentration, membrane tension, temperature, etc.). Ion channel provide pores for the passive diffusion of ions on the biofilm. Due to their high selectivity for ion, ion channel are generally classified as sodium (Na⁺ ), potassium (K⁺ ), calcium (Ca²⁺ ), chloride (Cl^- ), and non-specific cation channel. Ion channel is an important contributor to cell signal transduction and homeostasis. In addition to electrical signal transduction, ion channel also have many functions: regulating vascular smooth muscle contraction, maintaining normal cell volume, regulating glandular secretion, protein kinase activation, etc. Therefore, dysfunction of ion channel can lead to many diseases, and its mechanism research is particularly important.

MCE designs a unique collection of 1,495 small molecules related to ion channel, mainly targeting Na⁺ channel, K⁺ channel, Ca²⁺ channel, GABA receptor, iGluR, etc. It is an essential tool for research of cardiovascular diseases, Nervous system diseases and other diseases.

The transforming growth factor beta (TGF-β) signaling pathway is involved in many cellular processes in both the adult organism and the developing embryo including cell growth, cell differentiation, apoptosis, cellular homeostasis and other cellular functions. The TGF-β superfamily comprises TGF-βs, bone morphogenetic proteins (BMPs), activins and related proteins. Signaling begins with the binding of a TGF beta superfamily ligand to a TGF beta type II receptor. The type II receptor is a serine/threonine receptor kinase, which catalyzes the phosphorylation of the Type I receptor. The type I receptor then phosphorylates receptor-regulated SMADs (R-SMADs) which can now bind the coSMAD (e.g. SMAD4). R-SMAD/coSMAD complexes accumulate in the nucleus where they act as transcription factors and participate in the regulation of target gene expression. Deregulation of TGF-β signaling contributes to developmental defects and human diseases, including cancers, some bone diseases, chronic kidney disease, etc.

MCE designs a unique collection of 354 TGF-beta/Smad signaling pathway compounds. TGF-beta/Smad Compound Library acts as a useful tool for TGF-beta/Smad-related drug screening and disease research.

Targeted Protein Degradation (TPD) is a novel and promising approach to drug development. It shows great potential for targeting proteins traditionally considered "undruggable" due to the lack of enzymatic function and absence of binding sites by tagging them for degradation or recruiting natural degradation mechanisms.

Molecular glues are a type of small-molecule degraders that primarily induce novel interactions between E3 ubiquitin ligases and target proteins, forming ternary complexes that lead to protein ubiquitination and subsequent proteasomal degradation. Compared with PROTACs, molecular glues generally have lower molecular weights, higher cell permeability, and better drug-like properties. Additionally, the design of molecular glues is relatively simple, without the requirements for complex linkers and ligand optimization. As a result, molecular glues have gradually emerged as a promising therapeutic approach for various diseases.

Multiple types of molecular glues have been reported previously. Analysis of co-crystal complex structures reveals that CRBN-related molecular glues are more versatile. Therefore, MCE researchers select active molecules related to these targets as probes for artificial intelligence (AI) screening.Subsequently, molecular docking technology was used to verify whether the screened molecules retained the key pharmacophore features. Ultimately, we obtained 320 molecular glue analogs, and these compounds serve as powerful tools for the research of molecular glues.

Recently, significant advancements in tyrosine-targeting electrophiles have primarily occurred in the field of protein-protein interactions (PPIs), where cysteine residues are often underrepresented and novel chemistries are needed to address these interfaces. In this context, tyrosines are frequently more accessible compared to more buried binding sites. Moreover, they are commonly found at "hot spots," which are functional epitopes of PPIs, with 12.3% of the residues consisting of tyrosines. This prevalence is likely due to the hydrophobic nature of tyrosine, its ability to participate in aromatic π-interactions, and its capacity for hydrogen bonding. Beyond PPIs, some progress has also been made in covalent tyrosine targeting in other areas where more commonly addressed side chains are lacking. Even though tyrosine has a slightly lower pKa value compared to the protonated lysine side chain (approximately 10 vs. 10.5 for the unprotected amino acid side chains), significantly less progress has been made in the development of tyrosine-targeted covalent ligands compared to lysine. This is likely due to the reduced flexibility of the tyrosine side chain and the greater steric hindrance of its hydroxy group, which makes it more challenging to adopt suitable reaction geometries.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 124 fragment molecules which can target tyrosine residue and can be used for fragment-based covalent drug discovery.

MCE MBP Agarose (Dextrin) 6FF is prepared by covalently coupling dextrin to an agarose matrix. It features high binding capacity, excellent specificity, and superior ligand stability. It can achieve one-step purification of MBP fusion protein.

MCE SP Agarose HP is a high-resolution strong cation exchanger formed by covalently coupling sulfopropyl (SP) groups to agarose. This medium offers high binding capacity, high specificity, and excellent ligand stability, making it suitable for both laboratory-scale and large-scale industrial purification applications.

MCE DEAE Agarose HP is a high-resolution weak anion exchanger formed by covalently coupling diethylaminoethyl (DEAE) groups to agarose. This medium offers high binding capacity, high specificity, and excellent ligand stability, making it suitable for both laboratory-scale and large-scale industrial purification applications.

MCE Q Agarose HP is a high-resolution strong anion exchanger formed by covalently coupling quaternary ammonium (Q) groups to agarose. This medium offers high binding capacity, high specificity, and excellent ligand stability, making it suitable for both laboratory-scale and large-scale industrial purification applications.

MCE IMAC Agarose (NTA) 6FF is prepared by covalently coupling tetradentate nitrilotriacetic acid (NTA) to an agarose matrix. It features high binding capacity, excellent specificity, and superior ligand stability. The resin allows flexible chelation with metal ions such as Zn²⁺, Ni²⁺, or Cu²⁺, and is suitable for the purification of His-tagged recombinant proteins expressed in bacterial, mammalian, insect, and baculovirus systems.