Covalent Inhibitor Library

Cat. No.: Lib412062

Storage

Room temperature

Overview

•A unique collection of 97 covalent Inhibitors for high throughput screening (HTS) and high content screening (HCS) 

•Covalent inhibitors have excellent pharmacokinetic characteristics,and can overcome the resistance generated by mutations 

•Some covalent inhibitors have been approved by the FDA

•Structurally diverse, medicinally active, and cell permeable 

•Rich documentation with structure, IC50, and customer reviews 

•NMR and HPLC validated to ensure high purity

Product Details

Formulation	92 compounds pre-dissolved in 10mM DMSO，1 compounds pre-dissolved in 10mM H2O,4 compounds pre-dissolved in 2mM DMSO
Container	96 Well Format Sample Storage Tube With Screw Cap and Optional 2D Barcode
Stability	12 months -20°C in DMSO
	24 months -80°C in DMSO
Shipping	Blue ice or dry ice

Covalent Inhibitor Library Composition

Specifications

Storage

Room temperature

Application Protocols

Item-specific validated applications and dilutions: Not specified for this item; refer to CoA/Spec Sheet. The following generalized workflows are provided for research guidance only.

A. Biochemical covalent inhibition screen

1. Prepare 10 mM stocks in DMSO (or per manifest). Dispense to assay plates to achieve 1–10 µM final, ≤1% DMSO.
2. Preincubate enzyme (e.g., 0.1–1 nM to low µM, target-dependent) with compound 30 minutes at 25–37°C.
3. Initiate with substrate; record kinetic readout. Include time-dependence and jump-dilution controls to confirm covalency.
4. Counterscreens: GSH reactivity, redox interference, and aggregation controls (0.01% detergent).

B. Intact protein mass spectrometry target engagement

1. Incubate purified protein (1–10 µM) with compound (5–50 µM) in 20–50 mM HEPES, pH 7.4, 30–60 minutes.
2. Desalt; analyze by LC–MS for expected mass shift; perform peptide mapping for site localization.

C. Cell-based engagement via ABPP (competitive format)

1. Treat cells with library member; wash.
2. Label with broad-spectrum probe (e.g., IA-alkyne) under optimized conditions.
3. Click-chemistry tagging; enrich; LC–MS/MS to quantify competition at cysteine sites.

Always confirm solvent tolerance, include positive/negative controls, and refer to the item’s manifest for plate maps and concentrations.

Biological Roles

Item-specific biological roles or targets: Not specified for this item; refer to CoA/Spec Sheet. The library comprises multiple, distinct small molecules and does not correspond to a single biological entity.

General concepts (literature; for research use only):

• Mechanism: Covalent inhibitors form a chemical bond with nucleophilic residues in proteins (often Cys, Ser, Lys, Tyr), typically via Michael addition, nucleophilic substitution, or S–F exchange. This can yield time-dependent inhibition characterized by kinact/KI.
• Selectivity strategies: Achieved through complementary noncovalent recognition plus tuned intrinsic electrophile reactivity and positioning. Reversible-covalent chemotypes (e.g., cyanoacrylamides, boronate esters) offer a balance of potency and safety in biochemical systems.
• Proteome reactivity: Chemoproteomic profiling can reveal ligandable residues and off-target liabilities, informing warhead choice and scaffold optimization.
• Functional readouts: In biochemical assays, covalent engagement appears as time-dependent IC50 shifts, reduced by preincubation with nucleophiles (GSH) or mutation of reactive residues. In cells, target engagement can be assessed with CETSA, ABPP probes, or intact-protein MS.

Note: No clinical or therapeutic claims are made. This product is intended solely as a research tool for discovering and characterizing covalent interactions in biochemical and cellular systems.

Buffer Applications

Item-specific buffer recommendations: Not specified for this item; refer to CoA/Spec Sheet. The following are general considerations for assays with covalent inhibitors.

• Avoid strong nucleophiles: Minimize or eliminate DTT/β-mercaptoethanol in primary screens; prefer TCEP at minimal effective concentrations if a reductant is required (TCEP is less nucleophilic and thiol-free).
• Buffer choices: Phosphate (50 mM, pH 7.2–7.6) or HEPES (25–50 mM, pH 7.2–7.6) are broadly compatible. Tris contains a primary amine and may compete in some reactions at high pH—use cautiously.
• pH control: Reaction rates for many electrophiles increase with pH (higher nucleophile availability); choose assay pH to balance enzyme stability with desired reaction kinetics.
• Additives: Include low levels of nonionic detergents (0.01–0.05% Tween-20/NP-40 substitute) to reduce aggregation artifacts. Add 0.1–0.5 mg/mL BSA to mitigate nonspecific adsorption if compatible with the readout.
• Metal chelators: Use EDTA if metal-catalyzed side reactions are suspected; confirm compatibility with the target protein.
• DMSO tolerance: Validate assay performance at the highest anticipated DMSO %, including controls.

Practical tip: For targets requiring reduced cysteines, perform minimal pre-reduction with TCEP followed by rapid desalting (spin columns) before inhibitor addition to limit competing nucleophiles during covalent engagement.

Green Alternatives

While covalent inhibitor libraries are typically handled as DMSO stocks, greener handling strategies can reduce solvent burden and waste (general guidance; not item-specific):

• Lower DMSO percentage: Optimize assays to tolerate ≤0.1–0.5% DMSO, decreasing solvent usage per well.
• Alternative cosolvents (where compatible):
  • Water-first dissolutions with minimal DMSO “spikes” for moderately polar members.
  • Ethanol as a secondary solvent at ≤1% v/v, recognizing volatility and potential assay impacts.
  • Propylene carbonate or PEG400 as more benign options in specific biochemical assays (viscosity and background considerations apply).
• Miniaturization: Shift to 1536-well or acoustic dispensing to cut total solvent consumption and plastic waste.
• Closed-plate workflows: Use heat seals and low-evaporation lids to minimize solvent loss and VOC emissions.
• Waste segregation: Collect DMSO-rich waste separately to streamline disposal; avoid chlorinated solvents unless required.

Tradeoffs (literature):

• DMSO has unmatched solubilizing power and broad assay tolerance; greener substitutes may compromise solubility or assay signal.
• PEG-based vehicles can affect viscosity, diffusion, and optical readouts.

Recommendation: Pilot a solvent compatibility matrix for your assay format to balance green chemistry goals with data quality. Refer to the item’s manifest for any member-specific solubility notes before deviating from DMSO.

Pharmaceutical Uses

Item-specific pharmacopeial status or excipient roles: Not specified for this item; refer to CoA/Spec Sheet. This product is a discovery screening library and is not intended for use in human or veterinary applications.

Research/manufacturing context (general, non-clinical):

• Hit finding and SAR: Used in preclinical research workflows to identify covalent binders amenable to medicinal chemistry optimization. Outputs inform structure/reactivity relationships and guide selection of warheads consistent with developability goals.
• Developability assessments: Early evaluation of compound reactivity with glutathione, human microsomes/S9 (for stability), and plasma proteins can help triage chemotypes prior to scale-up (research-use context only).
• Analytical support: Establish reference materials and impurity profiles for promising members to enable later GMP synthesis if a compound advances in a separate, regulated program (outside the scope of this catalog item).
• Formulation screening (in vitro tools only): Solubility screens employing DMSO, co-solvents, or cyclodextrins can be performed to support biochemical/cellular testing.

Compliance note: No therapeutic, diagnostic, or clinical claims are made. The Covalent Inhibitor Library is furnished strictly for laboratory research use by qualified professionals.

Physical Properties

Item-specific physical specifications (BP, MP, density, UV cutoff, refractive index, pKa/logP, solubility): Not specified for this item; refer to CoA/Spec Sheet.

General/literature expectations for covalent inhibitor libraries (not item specifications):

• Physical state: Typically supplied as dry films or pre-plated solids in microplates/vials, or as DMSO solutions at defined concentrations for screening.
• Solubility: Most members are designed for solubility in DMSO (stock preparation commonly 10–50 mM); aqueous solubility varies widely and is scaffold-dependent. Cosolvent strategies include DMSO→buffer dilution, or addition of small percentages of ethanol/PEG400 (literature best practice).
• Stability considerations: Electrophilic warheads can be sensitive to nucleophiles, strong base, or prolonged exposure to moisture and heat. Sulfonyl fluorides and β-lactams are moisture/base sensitive; chloroacetamides can hydrolyze; acrylamides are generally more robust but can polymerize under radical conditions (literature).
• Volatility: Members are generally non-volatile solids; however, treat unknowns conservatively.
• Spectral properties: UV absorbance and fluorescence vary by scaffold; for HTS readouts, pilot scans (200–800 nm) or fluorescence interference tests are recommended to identify optical artifacts.

For quantitative values per member (e.g., purity %, exact concentration in solution format), consult the plate manifest/CoA for this specific lot.

Quality and Grades

Grade/Purity for this item: Not specified for this item; refer to CoA/Spec Sheet.

Library-specific quality considerations (general guidance):

• Identity and Purity: High-quality screening libraries are commonly QC’d by LC–MS and/or NMR to confirm identity and to assess purity, often targeting ≥90–95% purity per member. Exact criteria for this item are not specified here; defer to the CoA.
• Format and Concentration: Libraries may be supplied as dry films or as DMSO stocks at defined molarity per well. Verify plate maps, well positions, and concentrations in the manifest for error-free HTS integration.
• Salt form/counterions: Can influence solubility and stability; details are member-specific and should be documented in the manifest.
• Water/peroxide/metal trace limits: Not specified for this item; refer to CoA/Spec Sheet.
• Stabilizers/antioxidants: Not specified for this item; if present, they will be listed in the CoA. Some electrophiles may require inert-atmosphere storage or desiccation.
• Batch-to-batch consistency: For follow-up SAR, confirm re-synthesis or resupply traceability (lot numbers, analytical reports).
• Documentation provided (typical): plate layout (CSV/SD file), SMILES/SDF, CAS (if applicable), analytical summaries, and handling notes. Use these as the primary reference for screening setup and data annotation.

Reaction and Applications

This product is designed for research screening rather than as a reagent for synthetic transformations. The following outlines research applications for covalent inhibitor libraries (general guidance; not item-specific):

• Target discovery and validation: Identify proteins with accessible nucleophilic residues (commonly cysteine, serine, lysine, threonine, tyrosine) that can be selectively modified under physiological conditions.
• Lead identification: Covalent hits often yield durable target engagement and distinctive SAR. Warhead selection (e.g., acrylamide vs. chloroacetamide vs. sulfonyl fluoride) tunes reactivity and selectivity (literature).
• Chemoproteomics: Deploy in activity-based protein profiling (ABPP) or competitive labeling workflows to map reactive residues proteome-wide. Coupling with LC–MS/MS enables site-of-modification assignment.
• Fragment-based approaches: Reversible-covalent fragments (e.g., cyanoacrylamides, boronic acids) facilitate initial discovery with manageable reactivity and potential for elaboration.
• Counterscreens and triage: Include glutathione/n-acetylcysteine reactivity assays, thiol scavenger tolerance, time-dependence (kobs), and orthogonal readouts (MS target engagement) to filter PAINS or overly reactive chemotypes.
• Practical notes: Maintain low nucleophile backgrounds in buffers (minimize DTT/Tris), verify compound integrity by LC–MS after storage, and profile intrinsic reactivity (e.g., DTNB exchange, sulfhydryl reactivity) to contextualize potency.

Outcome: Appropriately triaged covalent hits can progress to structure-guided optimization and selectivity profiling across isoforms and homologs.

Reaction Conditions

This product is not intended for use as a stoichiometric reagent in organic synthesis; thus, there are no item-specific reaction conditions. The following general screening conditions are provided for research guidance (not item specifications):

• Biochemical enzyme assays: Preincubate enzyme with compound for 15–60 minutes at 25–37°C before substrate addition to allow covalent engagement. Typical initial screen concentration: 1–10 µM compound at 0.1–1% DMSO; follow with dose–response and time-dependence to estimate kinact/KI.
• Intact protein MS: Incubate target protein (1–10 µM) with compound (5–50 µM) in 20–50 mM HEPES or phosphate buffer, pH 7.4, 30–60 minutes at room temperature; quench as appropriate and analyze by LC–MS to detect mass shifts consistent with adduct formation.
• Cellular assays: Validate DMSO tolerance (≤0.1–0.5%), treat cells for 1–4 hours, then assess target engagement (e.g., ABPP with IA-alkyne probes or CETSA). Optimize exposure to minimize cytotoxic solvent effects.
• Counterscreens: GSH trapping (1–5 mM GSH) to profile intrinsic reactivity; competition with known covalent probe to confirm on-target residue engagement.

Note: Exact conditions depend on the target class, protein stability, and readout modality. Always corroborate activity with orthogonal assays to rule out assay interference.

Safety and Handling

Hazard classification (GHS, signal word, pictograms, H-statements) for this item: Not specified for this item; refer to SDS.

General safety guidance for covalent inhibitor libraries (not item-specific, defer to SDS):

• Risk profile: Members contain electrophilic warheads capable of reacting with biological nucleophiles (thiols, amines, serine/lysine residues). Handle as potentially toxic, sensitizing, or irritant.
• PPE: Lab coat, safety glasses, and appropriate chemically resistant gloves (e.g., disposable nitrile; consider double-gloving for DMSO handling). Work in a chemical fume hood or ventilated enclosure.
• Avoid exposure: Prevent skin contact, inhalation of dust/aerosols, and ingestion. Use microplate seals to minimize vapor/aerosol formation from DMSO stocks.
• Incompatibilities: Avoid contact with strong nucleophiles (amines, thiols such as DTT/β-ME), strong bases, and moisture for storage. Keep away from reducing agents that can quench electrophiles.
• First aid (overview; consult SDS): If on skin/eyes, rinse with water for at least 15 minutes; remove contaminated clothing. If inhaled, move to fresh air. Seek medical attention if symptoms persist.
• Spills and waste: Absorb DMSO solutions with inert material; dispose in accordance with institutional hazardous chemical waste procedures.
• Peroxide risk: Not typically relevant unless library members include peroxide-forming solvents; always check SDS for each supplied solvent.

Always consult the item’s SDS and institutional EHS guidance for authoritative instructions.

Solvent Selection

Item-specific solvent recommendations: Not specified for this item; refer to CoA/Spec Sheet. The following are general best practices for small-molecule screening libraries.

• Primary solvent: DMSO is the de facto standard due to broad solubilization capacity and assay compatibility at ≤0.5–1% v/v in most biochemical/cell assays (literature best practice).
• Co-solvents: Ethanol (≤1–2% v/v), acetonitrile (≤0.5–1% v/v), or PEG400 (≤2–5% v/v) can assist dissolution of hydrophobic members; verify assay tolerance.
• Aqueous dilution: Prepare intermediate DMSO stocks and titrate into buffered media. Vortex and brief sonication aid dissolution. Filter if particulate persists (0.2 µm PTFE/NYLON), mindful not to adsorb scarce material.
• Avoid nucleophilic additives: Free thiols (DTT, β-ME), high primary amine buffers (e.g., Tris at high pH), and strong bases can prematurely quench electrophiles.
• Container compatibility: Use low-binding polypropylene plates/tubes; avoid polystyrene for hydrophobic compounds.

Comparison (general):

• DMSO: highest solubilizing power; hygroscopic; good cell compatibility at low %.
• Ethanol: volatile; acceptable up to ~1% in many assays; can extract plasticizers.
• Acetonitrile: strong solvent; may denature proteins; use sparingly.
• PEG400: increases apparent solubility; viscous; may affect signal.

Always verify solvent composition limits for your specific assay and refer to the item’s manifest for any member-specific notes.

Storage and Reconstitution

Item-specific storage/shipping: Storage Conditions = Room temperature (per Product Data). Shipped In: Not specified for this item; refer to CoA/Spec Sheet.

General guidance for covalent inhibitor libraries (not item-specific; follow the label if different):

• As-supplied plates/vials: Store sealed at room temperature in a desiccated, dark environment. Minimize exposure to moisture and heat to preserve electrophilic warheads.
• Reconstitution: If provided as dry films, dissolve each member in anhydrous DMSO to the desired stock concentration (commonly 10 mM; verify manifest). Mix by vortex and brief sonication if needed. Record final concentrations and volumes.
• Aliquoting: Prepare single-use aliquots to avoid repeated freeze–thaw and moisture uptake. Use low-bind polypropylene tubes/plates with high-quality seals.
• Stock storage: DMSO stocks are often stored at −20 to −80°C, protected from light. Allow to equilibrate to room temperature before opening to prevent condensation; promptly reseal after use.
• Stability checks: Periodically assess a subset by LC–MS to monitor degradation (hydrolysis, substitution). Discard wells/aliquots showing precipitation, discoloration, or anomalous assay behavior.

Note: Where specific storage temperatures, concentrations, or stabilizers are provided in the CoA/Spec Sheet for this SKU, those instructions take precedence over the general guidance above. For research use only.

Structure and Identity

Item-specific identifiers such as Molecular Formula, Molecular Weight, SMILES, InChI, and CAS: Not specified for this item; refer to CoA/Spec Sheet.

Overview (general, library-level):

• This product is a curated collection of small-molecule covalent inhibitors rather than a single chemical entity. As such, there is no single structure or unique identifier.
• Libraries of this class typically comprise electrophile-bearing scaffolds designed to form irreversible or reversible-covalent bonds with nucleophilic residues in proteins (literature):
  • Common “warheads”: acrylamides, chloroacetamides, vinyl sulfones/sulfonamides, sulfonyl fluorides (SuFEx), boronic acids/esters, nitriles, cyanoacrylamides, β-lactams, epoxides, isothiocyanates.
  • Scaffolds often span diverse heteroaromatics (e.g., pyridines, quinazolines, imidazopyridines) and privileged cores for medicinal chemistry exploration (literature).
• Stereochemistry: Individual members may be achiral or bear defined stereocenters; details are member-specific (not specified for this item).
• 2D structural description (general): A typical member features a recognition scaffold (heteroaryl/aryl or bicyclic framework) linked via a spacer (alkyl/ether/urea/amide) to an electrophilic functional group capable of Michael addition, nucleophilic substitution, or S–F exchange with target residues.

Documentation: The definitive listing of member structures, plate maps, and identifiers should be taken from the supplied plate manifest and CoA/Spec Sheet (not provided in this record).

Synthetic Utility

Not a primary use case: This product is a collection of finished small molecules, not a reagent or building block set. Therefore, it is not typically employed as a synthetic reagent.

General notes (literature context):

• Some library members may be synthetically modifiable (e.g., handle diversification via amide coupling, SNAr, or Suzuki cross-coupling on the scaffold). However, such transformations are member-specific and require knowledge of exact structures and protecting-group strategies.
• Warhead transformation: Up- or down-tuning intrinsic reactivity (e.g., acrylamide vs. cyanoacrylamide; chloroacetamide to acrylamide; sulfonyl fluoride to sulfonyl chloride) is feasible in medicinal chemistry follow-up, but is beyond the scope of the supplied library.
• Stability during synthesis: Electrophiles such as β-lactams, epoxides, and sulfonyl fluorides demand mild conditions and careful base control to avoid decomposition.

Recommendation: For SAR expansion, obtain individual members as neat compounds with full characterization, or resynthesize with route-appropriate protections. The library itself should be reserved for screening and hit confirmation rather than as a pool of synthetic starting materials.

Target Specificity

Item-specific target list, antigen/epitope, species reactivity, or clone/isotype: Not specified for this item; refer to CoA/Spec Sheet.

General context (literature):

• Covalent inhibitor libraries typically contain chemotypes biased toward nucleophile-bearing active sites, with a prevalence of cysteine-targeting warheads (e.g., acrylamides, chloroacetamides). Other residues (Ser, Lys, Tyr, Thr) may be addressed by tailored electrophiles (e.g., sulfonyl fluorides for Ser/Tyr; fluorophosphonates for serine hydrolases; boronic acids for catalytic serines in proteasome-like systems).
• Specificity emerges from both recognition elements (noncovalent binding) and kinetic selectivity (balanced intrinsic reactivity). Off-target risks increase with highly reactive chemotypes; triage via proteome-wide profiling and selectivity panels is recommended.

For a definitive list of targets or bias encoded in this specific library, consult the supplier’s library description, plate manifest, and any provided target annotations.