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Cyclic peptide library have advantages such as high affinity, high selectivity, and suitability for targeting protein–protein interactions. Through DEL synthesis technology, the library size can achieve hundreds of millions. DEL cyclic peptide library have advantages like low cost andhigh screeing efficiency, making them valuable for discovering lead compounds against challenging drug targets.

This cyclic peptide library is constructed with unnatural amino acids as building block, synthesized through DNA-compatible chemical reactions. Each cyclic peptide consist of six amino acids and constrained conformations such as side-chain cross-linking, disulfide bonds, and macrocyclization. These cyclic peptides exhibit significantly improved stability and druggability compared with linear peptides, filling the gap between small molecules and macromolecular biologics. Each cyclic peptide is uniquely conjugated to a DNA barcode sequence for molecular identification and sequencing decoding.

MCE’s cyclic peptide library has8 independent sub-libraries, with a total molecular diversity of 1.2 billion. It is constructed via multi-round combinatorial assembly of building blocks and diverse cyclization strategies, facilitating the discovery of cyclic peptide leads for undruggable targets.

Macrocyclic scaffolds are increasingly valued in modern drug discovery for their exceptional activity against undruggable targets (proteases, kinases, PPIs). 2026 marks a key commercial breakthrough for oral macrocyclic peptides: enlicitide, the world’s first oral PCSK9 macrocyclic peptide, has received FDA approval. Macrocyclic candidates targeting KRAS and other classic undruggable targets have also entered clinical development, validating macrocyclization as an effective strategy to overcome druggability barriers.

Two core R&D directions lead current macrocyclic drug design: AI-driven de novo generation and structural optimization of small-molecule macrocycles, and macrocyclic peptides based on sequence design and conformational engineering. Macrocycle druggability hinges on embedded linkers, which determine cyclization efficiency, final conformation and drug-like properties. Bifunctional reaction orthogonality is the core linker selection criterion. Our linker library enables stepwise intramolecular cyclization with suppressed side reactions, accommodates varied ring sizes, and covers three key reaction systems: amide condensation, nucleophilic substitution and CuAAC click chemistry.

Built on classical macrocyclization systems, the library is processed through reaction classification, bifunctional orthogonality evaluation, novelty clustering and redundancy removal, with PROTAC long-chain and ADC cleavable linkers explicitly excluded. Featuring rigid, semi-rigid and flexible scaffolds, it is widely applicable to small-molecule macrocycle synthesis and linear peptide cyclization.

The discovery of hit molecule is a cornerstone of drug development. Among the diverse tools available, DNA-encoded libraries have emerged a revolutionary platform for high-throughput screening. Compared with traditional HTS, DEL features shorter screening processes, lower costs, simpler assays, and larger library capacities.

DEL Construction utilizes split-and-pool synthesis, a combinatorial chemistry approach that involves iterative splitting, reaction, and pooling. This strategy enables rapid, exponential assembly of fragments in minimal steps without the need for individual compound synthesis andassoicicated isolation or purification steps, thus greatly reducing overall costs. The technology enables simultaneous affinity screeningof massive compound collections to target proteins in a single step. By coupling chemical structures with unique DNA barcodes, each compound is tagged with a distinct DNA sequence for convenient tracking and decoding.DELs readily enable the construction and efficient screening of libraries containing millions to billions of compounds. As a result, DEL screening combines the dual advantages of high efficiency and low cost, making DEL a transformative technology in modern drug discovery.

The DEL kit consists of 50 independent libraries with a total scale of 100 billion compounds. It is constructed through stepwise combinatorial chemistry strategies involving 2-, 3-, and 4-round synthesis. By employing diverse scaffolds and flexible linking strategies, it encompasses various ring systems, linear frameworks, and heterocyclic structures. Screening can be achieved solely through affinity, independent of target-specific activity detection methods. This library is suitable for DEL screening against a wide range of targets.

DEL technology enables the simultaneous screening of millions or billions of compounds in a single tube by covalently linking each small molecule with a unique DNA sequence. Traditional DEL screening primarily focuses on identifying non-covalent binding molecules, where interactions with the target are reversible. In contrast, DNA‑encoded covalent library is an ultra‑high‑throughput screening library developed on the basis of conventional DNA‑encoded library technology. It incorporates controllable electrophilic covalent warheads capable of forming irreversible covalent bonds with amino acid residues at the active sites of target proteins, including Cys, Lys, Ser, Tyr, and others. This covalent binding enhances binding affinity, prolongs residence time at the target site, and has the potential to overcome challenges associated with traditional non-covalent inhibitors, such as drug resistance or off-target effects.

Each compound in the library contains both a binding domain and an electrophilic warhead. It first recognizes and binds to the target through non covalent interactions, and then forms a stable covalent bond with key amino acid residues to achieve irreversible inhibition. This library is specifically designed for the discovery of potent, long lasting, and highly selective covalent inhibitors, particularly for undruggable targets such as kinases, GPCRs, proteases, and mutant oncoproteins. Each molecule is uniquely labeled with a DNA barcode for molecular identification and sequencing decoding.

This library is an advanced and highly diverse collection, consists of 35 independent sub-libraries with a total scaleof 14 million compounds, It incorporates over 14 experimentally validated covalent warheads capable of targeting cysteine, lysine, arginine, aspartic acid and glutamic acid. This library is constructed with diverse drug like core scaffolds and integrated controllable covalent warheads, it features structural diversity, reaction spec