Chemical probes

Chemical probes are simply reagents with high potency, selectivity and cell-permeability which play important roles in both fundamental and applied biological research. In their most common application, chemical probes can establish the tractability of a specific target. They are used to interrogate the relationship between a target and its phenotype (biological tractability) as well as an ability to modulate that phenotype using a small molecule. Otherwise, chemical probes also have had a major impact in enabling and accelerating discoveries along the path to pioneer medicines. They have helped to improve the understanding of targets and pathways and have created opportunities for proprietary drug discovery efforts to an extent that would not have been possible otherwise.

MCE provides a unique collection of 281 chemical probes with high potency (at least 100 nM potency), selectivity (at least 10-fold selectivity against any other target) and cell-permeability (at least 10 μM potency). MCE Chemical probe library is a useful tool for target identification and mechanism research.

Sulfonyl fluoride (-SO₂F) overcomes the bottleneck of target selectivity in traditional covalent warheads through its unique chemical and biological properties, which rely heavily on cysteine (Cys) residues. Featuring high stability and tunable electrophilicity under physiological conditions, it can target a wide range of nucleophilic residues including lysine (Lys), tyrosine (Tyr), serine (Ser), and histidine (His). It offers the advantages of a broader druggable space, lower off-target risks, and long-lasting efficacy, with numerous reported cases in the research of covalent inhibitors, Molecular glue, PROTACs, and chemical biology probe development.

MCE constructs a highly diverse sulfonyl fluoride fragment library based on the reactivity, stability and physiological compatibility of sulfonyl fluoride. The library contains 1000 efficiently synthesized and stable sulfonyl fluoride fragments, which ensure precise reactivity of the warhead and retain sufficient derivatization space for subsequent optimization. Combined with the modular strategy of SuFEx click chemistry, it enables versatile modification of compounds and functionalization of complex molecules, improves the efficiency of structural optimization and rapidly expands druggability, making it suitable for high-throughput probe and custom covalent library construction. It provides an efficient research tool for the development of broad-spectrum covalent inhibitors targeting Lys/Tyr/Ser/His, covalent PROTACs for E3 ligases and chemical biology probe development, meeting the requirements of modern drug research for high throughput, high success rate and high derivatization potential.

This library contains 1,162 sulfonyl fluoride fragments with high structural diversity, favorable drug-like properties and tunable electrophilicity. It is well suited for precise targeting of non-Cys residues and meets the criteria of simple structure and high derivatization potential. It effectively improves

Fragment-based drug discovery (FBDD) is well suited for discovering both drug leads and chemical probes of protein function; it can cover broad swaths of chemical space and allows the use of creative chemistry. Fragment-based drug discovery is well-established in industry and has resulted in a variety of drugs entering clinical trials, with two, vemurafenib and venetoclax, already approved. FBDD also has key attractions for academia. Notably, it is able to tackle difficult or novel targets for which no chemical matter may be found in existing HTS collections.

MCE designs a unique collection of 23,342 fragment compounds, 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 library is an important source of lead-like drugs.

Unlike the 20 natural amino acids commonly found within living organisms, non-natural amino acids are synthesized through chemical or biosynthetic methods, thereby being endowed with unique chemical properties or biological activities. In drug development, these amino acids can be utilized to design novel pharmaceutical molecules that may exhibit superior pharmacological characteristics, such as increased selectivity, improved pharmacokinetic profiles, or reduced toxicity. In biomedical research, uon-natural amino acids can act as biological markers or probes for investigating biological processes like cell signaling, protein conformation, and protein-protein interactions. In addition, non-natural amino acids can also be used in the field of agriculture to develop new pesticides, plant growth regulators and so on.

Small molecule covalent inhibitors, or irreversible inhibitors, are a type of inhibitors that exert their biological functions by irreversibly binding to target through covalent bonds. Compared with non-covalent inhibitors, covalent inhibitors have obvious advantages in bioactivity, such that covalent warheads can target rare residues of a particular target protein, thus leading to the development of highly selective inhibitors and achieving a more complete and continued target occupancy in living systems. In recent years, the distinct strengths of covalent inhibitors in overcoming drug resistance had been recognized. However, toxicity can be a real challenge related to this class of therapeutics due to their potential for off-target reactivity and has led to these drugs being disfavored as a drug class. The drug design and optimization of covalent inhibitors has become a hot spot in drug discovery.

MCE covalent inhibitor library contains 5,994 small molecules including identified covalent inhibitors and other molecules having common covalent reactive groups as warheads, such as acrylamides, activated terminal acetylenes, sulfonyl fluorides/esters, cloracetamides, alkyl halides, epoxides, aziridines, disulfides, etc.

MCE Covalent inhibitor Library plus, with more powerful screening capability, further complement Covalent inhibitor Library (HY-L036) by adding some fragment compounds with covalent warheads.

Unnatural amino acids (UAAs), also referred to as non-canonical amino acids (ncAAs) or non-proteinogenic amino acids, are a class of amino acids that are distinct from the 20 standard natural amino acids. They can be obtained through chemical synthesis, biosynthesis, and other approaches, with structural diversity far exceeding that of natural amino acids. UAAs are mainly including naturally occurring non-canonical amino acids, chemically synthesized amino acids, and biosynthetic amino acids, which provide a molecular basis for protein function design.

UAAs exhibit significant value in multiple fields. They can optimize the pharmacokinetic properties of peptide drugs and peptidomimetics, modify enzyme functions and endow them with new biological activities, thereby overcoming the limitations of traditional peptide drugs and expanding the chemical space . Meanwhile, UAAs can serve as molecular probes to analyze protein-protein interactions and investigate the regulatory mechanisms of protein functions.

MCE has compiled a UAAs Fragment Library comprising nearly a thousand unnatural amino acid fragments with extensive coverage of chemical space and enhanced structural diversity. This compound library can be widely applied in peptide synthesis, drug design, and protein engineering.

Small molecule covalent inhibitors, or irreversible inhibitors, are a type of inhibitors that exert their biological functions by irreversibly binding to target through covalent bonds. Compared with non-covalent inhibitors, covalent inhibitors have obvious advantages in bioactivity, such that covalent warheads can target rare residues of a particular target protein, thus leading to the development of highly selective inhibitors and achieving a more complete and continued target occupancy in living systems. In recent years, the distinct strengths of covalent inhibitors in overcoming drug resistance had been recognized. However, toxicity can be a real challenge related to this class of therapeutics due to their potential for off-target reactivity and has led to these drugs being disfavored as a drug class. The drug design and optimization of covalent inhibitors has become a hot spot in drug discovery.

MCE covalent inhibitor library contains 1,546 small molecules including identified covalent inhibitors and other bioactive molecules having common covalent reactive groups as warheads, such as acrylamides, activated terminal acetylenes, Sulfonyl fluorides/esters, cloracetamides, alkyl halides, epoxides, aziridines, disulfides, etc.

Small molecule covalent inhibitors, or irreversible inhibitors, are a type of inhibitors that exert their biological functions by irreversibly binding to target through covalent bonds. Compared with non-covalent inhibitors, covalent inhibitors have obvious advantages in bioactivity, such that covalent warheads can target rare residues of a particular target protein, thus leading to the development of highly selective inhibitors and achieving a more complete and continued target occupancy in living systems. In recent years, the distinct strengths of covalent inhibitors in overcoming drug resistance had been recognized. However, toxicity can be a real challenge related to this class of therapeutics due to their potential for off-target reactivity and has led to these drugs being disfavored as a drug class. The drug design and optimization of covalent inhibitors has become a hot spot in drug discovery.

MCE Lead-like Covalent Screening Library offers a valuable resource of 1,049 lead-like compounds with commonly used covalent warheads. These warheads, such as acrylamide, activated terminal alkyne, acyloxymethyl ketone, and boronic acid, are capable of reacting with specific amino acid residues, including cysteine, lysine, serine, and histidine. The inclusion of these reactive warheads in the library allows researchers to explore the potential of covalent inhibition, a powerful approach in drug discovery.

Fragment-based drug discovery (FBDD) is well suited for discovering both drug leads and chemical probes of protein function. 3-dimensionality (3D) diversity is pivotal because the molecular shape is one of the most important factors in molecular recognition by a biomolecule. There is a developing appreciation that 3D fragments could offer opportunities that are not provided by 2D fragments.

MCE 3D Diverse Fragment Library consists of 5,400 non-flat fragment-like molecules (average Fsp3 value 0.58). More than 4,700 fragment compounds contain at least one chiral center in the structure. The key concepts that underlie the library design were 3D shape, structural diversity, reactive functionality and fragment-like. This 3D Diverse Fragment Library brings higher fragment hit optimization and increases the likelihood to find innovative hits in FBDD.