m-PEG3-Mal , CAS No.M1444961

CAS: M1444961 Cat. No.: M1444961 Fórmula: C₁₄H₂₂N₂O₆ Peso molecular: 314.33

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Visão geral

m-PEG3-Mal is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs.

Specifications

Condições de armazenamento de armazenamento

Store at -20°C

Enviado em

Ice chest + Ice pads

Este produto requer transporte de cadeia fria. Serviços terrestres e outros serviços econômicos não estão disponíveis.

Nomes e identificadores

• Peso molecular: 314.33

Application Protocols

No item-specific, validated application protocols are provided in the Product Data. For general guidance, please refer to the Reaction Conditions and Buffer Applications sections for typical thiol–maleimide conjugation setups. Always optimize conditions (pH, stoichiometry, temperature, time) for your specific substrate and analytical readouts.

Biological Roles

This product is a synthetic bioconjugation linker and does not possess an intrinsic biological role. The following notes describe its utility in biochemical systems (general/literature):

• Cysteine targeting: maleimide selectively reacts with thiol side chains of cysteine residues, enabling site-specific modification of proteins and peptides under mild, near-neutral conditions.
• PEG spacer effects: the triethylene glycol (PEG3) segment imparts hydrophilicity, reduces nonspecific adsorption, and can improve solubility of appended hydrophobic moieties in aqueous media.
• Conjugate behavior: installing a short PEG spacer can modulate hydrodynamic radius, decrease aggregation, and reduce surface stickiness of modified biomolecules, which can benefit assay performance and purification.
• Nonbiological reactivity: no receptor binding or enzyme inhibition should be inferred; any observed biological effects stem from the payload or the modified biomolecule, not from the linker itself.

Research-use limitation:

• For research use only (as stated in Product Data). Not for diagnostic, clinical, or therapeutic applications.

Buffer Applications

While not a buffer component itself, m-PEG3-Mal is commonly used in buffered aqueous media for thiol–maleimide conjugation. Practical guidance (literature/general):

• Optimal pH: 6.5–7.5 to maximize thiol addition while minimizing maleimide hydrolysis. Common choices: 50 mM phosphate, HEPES, or citrate buffers.
• Ionic strength: 50–150 mM NaCl helps maintain protein solubility and reduces nonspecific interactions.
• Reducing conditions: Avoid free thiol reductants like DTT/βME during coupling; prefer TCEP pre-reduction followed by removal or use at low micromolar levels.
• Metal chelation: 0.5–1 mM EDTA can suppress metal-catalyzed thiol oxidation without interfering with maleimide.
• Co-solvent: 0–10% DMSO or DMF to aid solubility of hydrophobic partners while preserving protein stability.

Example buffer recipes (general guidance):

• Conjugation buffer A: 50 mM phosphate, 100 mM NaCl, 1 mM EDTA, pH 7.0.
• Conjugation buffer B: 50 mM HEPES, 50 mM NaCl, pH 7.2.

Notes:

• Degas buffers (nitrogen/argon sparge) to reduce thiol air oxidation.
• Filter (0.22 µm) to remove particulates. Always validate conditions for your specific protein or substrate.

Green Alternatives

Greener considerations focus on solvent choice and linker selection. The maleimide–PEG3 motif is already relatively enabling for aqueous processes due to PEG’s hydrophilicity.

Greener solvent choices (literature/general):

• Prefer water-buffered systems with minimal organic co-solvent (≤10% DMSO/ethanol/ACN) where protein stability allows.
• Replace DMF with glycerol, ethanol, 2-propanol, or propylene carbonate if compatible with the biomolecule and kinetics; validate stability and reaction rates.

Comparison of solvent options (general):

• Water + ≤10% DMSO: strong balance of reactivity and EHS profile; minimizes VOCs versus neat organics.
• Ethanol or 2-propanol (≤20%): greener than DMF/ACN; may slow reaction or affect protein folding—screen empirically.
• Cyclic carbonates (propylene/ethylene carbonate): high-boiling, low vapor pressure; useful for small-molecule thiol additions; limited protein use.

Linker/chemistry alternatives:

• Alternative thiol-selective chemistries (e.g., haloacetamides, pyridyl disulfides) can be used when maleimide stability is a concern; each has trade-offs in selectivity, reversibility, and required conditions.

Trade-offs:

• Reducing organic content can slow kinetics or reduce solubility of hydrophobic partners. Balance EHS gains with process performance; small DoE screens are recommended.

Pharmaceutical Uses

No therapeutic claims are made. The following describes formulation/manufacturing-relevant roles in research and development (general/literature):

• Bioconjugation handle: m-PEG3-Mal is used in process development for site-selective cysteine modification of proteins, peptides, and antibodies to install small molecules, imaging agents, or affinity tags.
• Spacer tuning: the PEG3 segment provides a compact, hydrophilic spacer that can reduce aggregation and improve chromatographic behavior of conjugates during purification (SEC, IEX, or RP-HPLC).
• Excipient considerations: While not a conventional excipient, short PEG linkers can influence solubility and stability of conjugates; screening during formulation development can identify optimal linker length and buffer conditions.
• Analytical development: The discrete mass of PEG3–maleimide linkers facilitates intact mass confirmation and peptide mapping versus polydisperse PEGs.

Regulatory note:

• Any GMP use requires appropriate vendor qualification, CoA review, impurity profiling, and validation of residual solvents/reagents. This catalog item is for research use only (per Product Data).

Physical Properties

Item-specific properties (specifications):

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.
• Other specifications (bp, mp, density, refractive index, water/peroxide content, metals, UV cutoff): Not specified for this item; refer to CoA/Spec Sheet.

General/literature expectations for this reagent class (for context only):

• Physical state: typically a low-melting solid or viscous syrup, depending on exact substitution and purity (literature/general for short PEG–maleimides).
• Solubility (qualitative): freely soluble in polar aprotic solvents (DMSO, DMF, acetonitrile) and miscible with water/buffers at useful concentrations due to the PEG3 chain (literature).
• Hygroscopicity: PEG chains can be hygroscopic; minimize atmospheric exposure to prevent moisture uptake (general practice).
• Stability: maleimide ring is susceptible to hydrolysis at elevated pH, forming maleamic acid with loss of thiol reactivity; more stable at mildly acidic to neutral pH (literature).

Notes:

• Use the item’s CoA/Spec Sheet for any numeric or acceptance-criteria values required for QC or method development.
• If precise solubility, water content, or assay is critical to your application, verify by a small-scale pretest and consult the SDS/CoA.

Quality and Grades

Item-specific grade/purity information:

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

Guidance on quality considerations for m-PEG3-Mal (general):

• Monodispersity: "m-PEG3" indicates a discrete triethylene glycol spacer rather than a polydisperse PEG distribution. Discrete linkers support reproducible bioconjugation stoichiometry and analytical characterization.
• Purity vs. function: even trace maleamic acid (hydrolyzed) impurity reduces effective thiol-reactive content. For critical applications, verify active maleimide content via a thiol titration assay or LC-MS.
• Low-UV absorbance: For HPLC analytics of conjugates, ensure solvent- and reagent-grade backgrounds are sufficiently low in UV-active impurities to enable baseline resolution.
• Stabilizers: Typically none are added to maleimide–PEG reagents; if a stabilizer is present, it should be disclosed on the CoA. Absence/presence of stabilizers can influence downstream analytics and should match your method needs.
• Endotoxin/bioburden: For biochemical work, consider prefiltering solutions (0.22 µm) and using low-endotoxin buffers if relevant. If endotoxin limits are critical, request documentation or perform in-house testing.

Documentation: Use the lot-specific CoA/Spec Sheet for acceptance criteria, assay method, residual solvents, and impurity profiles relevant to regulated or QC-heavy workflows.

Reaction and Applications

Core reactivity (literature/general):

• Selective thiol conjugation via Michael addition of cysteine or other thiols to the maleimide double bond, yielding a stable thioether. Reaction is fastest at pH ~6.5–7.5 where thiols are nucleophilic yet maleimide ring opening is minimized.

Primary applications:

• Protein/peptide conjugation: site-specific attachment to free cysteines for fluorophore labeling, PEGylation, enrichment handles, or immobilization.
• Small-molecule coupling: introduction of a short hydrophilic PEG3 spacer between a thiol-bearing entity and a methoxy-terminated handle.
• Surface/particle modification: grafting to thiol-functionalized surfaces (e.g., Au–thiol SAMs, thiolated polymers) to tune hydrophilicity and spacing.

Practical tips:

• Avoid competing thiols (e.g., DTT, β-mercaptoethanol). Prefer TCEP for reducing disulfides; remove excess TCEP before conjugation or keep ≤0.5–1 mM to limit quenching.
• Control pH: use buffers such as phosphate/HEPES at pH 6.8–7.2. Above pH 8, maleimide hydrolysis to maleamic acid reduces reactivity.
• Stoichiometry: for proteins, 1.1–5.0 equivalents per accessible cysteine is common; monitor by intact MS or Ellman’s assay.
• Kinetics: reactions often reach completion within 15–120 minutes at room temperature; gentle agitation improves mass transfer.
• Stability of adducts: thioether–maleimide succinimides can undergo retro-Michael exchange at high pH; ring hydrolysis post-conjugation (by mild base or hydrolysis) can stabilize the linkage if needed (literature strategy).

Quality control:

• Track conversion by LC-MS or SDS-PAGE (for biomolecules). Purify by SEC, spin desalting, or RP-HPLC depending on system.

Reaction Conditions

General guidance for thiol–maleimide conjugation with m-PEG3-Mal (literature/practice):

• Substrates: free thiol-containing proteins/peptides or small molecules. Reduce disulfides with TCEP (0.5–5 mM, 15–60 min), then remove excess reductant or keep minimal residual levels.
• Buffer: 25–100 mM phosphate or HEPES, 0–150 mM NaCl, 0.5–1 mM EDTA, pH 6.8–7.2. Degas to minimize oxidation.
• Solvent: aqueous buffer with 0–10% DMSO/DMF to dissolve m-PEG3-Mal. Prepare fresh stock solutions (e.g., 10–100 mM in anhydrous DMSO) immediately before use.
• Stoichiometry: 1.1–5.0 equivalents of m-PEG3-Mal per accessible thiol for proteins; 1.0–1.5 equivalents for small molecules.
• Temperature/time: 20–25°C for 0.25–2 h. Lower temperatures (4–10°C) can be used for sensitive proteins with longer reaction times.
• Quenching: remove unreacted linker by SEC/desalting or quench residual maleimide with a low-molecular-weight thiol (e.g., cysteine) if appropriate.
• Post-conjugation stabilization (optional): mild hydrolysis of the succinimide ring (e.g., pH 8.5 buffer for 1–2 h at RT) can mitigate retro-Michael exchange (literature). Validate to avoid protein damage.

Monitoring and analytics:

• LC-MS (intact and peptide mapping), Ellman’s assay for free thiols, SDS-PAGE shift, or HIC/SEC for conjugate profiling.

Note: Parameters above are general literature guidance and should be optimized per system.

Safety and Handling

Item-specific hazard data:

• Signal Word: Not specified for this item; refer to SDS.
• H-Statements / GHS Classification / Pictograms: Not specified for this item; refer to SDS.

General safety considerations for maleimide–PEG reagents (literature/experience-based):

• Maleimides are electrophilic Michael acceptors and can alkylate thiols. Avoid skin contact, inhalation of dust/aerosols, and eye exposure.
• PPE: laboratory coat, safety glasses, and appropriate chemical-resistant gloves (e.g., nitrile). Use in a fume hood when handling powders/solutions or when weighing.
• Incompatibilities: strong bases (promote maleimide ring opening), strong nucleophiles, and reducing agents that contain free thiols (DTT/β-mercaptoethanol can consume maleimide).
• First aid (overview; defer to SDS): rinse skin/eyes with water for at least 15 minutes upon contact; remove contaminated clothing; seek medical attention if symptoms persist. If inhaled, move to fresh air. If swallowed, rinse mouth—do not induce vomiting unless directed by medical personnel.
• Special risks: moisture uptake may lead to hydrolysis over time; keep container tightly closed and minimize exposure to humid air. Avoid prolonged contact with basic buffers (pH > 8) to preserve thiol reactivity.

Always consult the product-specific SDS for authoritative hazard classification and emergency procedures.

Solvent Selection

Role and polarity (general):

• m-PEG3-Mal is a polar, water-compatible linker with high solubility in polar aprotic solvents and good compatibility with aqueous buffers due to the PEG3 segment.

Typical solvent choices (literature/practice):

• Stock solutions: anhydrous DMSO or DMF (5–100 mM) prepared immediately before use to limit hydrolysis.
• Reaction media for bioconjugation: aqueous buffers (pH 6.5–7.5) such as PBS, phosphate, HEPES, or citrate with 0–20% co-solvent (DMSO/DMF/ACN) to aid solubilization of hydrophobic partners.
• Poor choices: strong basic buffers (≥ pH 8.5) accelerate maleimide ring opening; avoid alcohol-rich media if they compromise protein stability.

Selection guidance:

• Choose DMSO for maximum solubility and minimal nucleophilicity; DMF/ACN are alternatives when DMSO is incompatible with analytics.
• For protein conjugations, limit organic co-solvent to ≤10–20% v/v to preserve protein structure.
• For small-molecule thiol additions, neat polar aprotics or mixed aqueous/organic systems are effective; degassing can reduce competing thiol oxidation.

Comparison (general):

• m-PEG3-Mal vs longer PEGn-Mal: shorter PEG (n=3) offers compact spacing and lower hydrodynamic drag; longer PEG improves solubility and reduces aggregation but may alter binding/sterics.

Storage and Reconstitution

Item-specific conditions from Product Data:

• Storage Conditions: Store at -20°C.
• Shipped In: Ice chest + Ice pads.
• Research Use Note: For research use only.

General handling and reconstitution guidance (literature/practice):

• Minimize moisture: allow the container to warm to room temperature in a desiccator before opening to prevent condensation. Reseal promptly and, if possible, purge headspace with inert gas.
• Working solutions: prepare fresh stocks in anhydrous DMSO or DMF (e.g., 10–100 mM) immediately prior to use. Avoid repeated freeze–thaw of solutions; aliquot and store at ≤−20°C if stability has been verified.
• Aqueous stability: maleimide is susceptible to hydrolysis, especially at pH > 7.5. Prepare aqueous working solutions immediately before conjugation and use within the same day.
• Light/temperature: store protected from light and heat. Short exposures to ambient light are typically acceptable, but long-term storage is best at −20°C in dry, dark conditions.

Disposal:

• Dispose of unused material and contaminated consumables as hazardous chemical waste in accordance with institutional and local regulations.

For any lot-specific stability or reconstitution instructions, consult the CoA/Spec Sheet.

Structure and Identity

Brief description: m-PEG3-Mal is a thiol-reactive, monodisperse PEG linker bearing a terminal maleimide and a methoxy cap on the opposite end. It is widely used for site-selective cysteine conjugation on proteins, peptides, and other thiol-containing substrates.

Item-specific identifiers from Product Data:

• CAS: M1444961 (catalog identifier; Not a standard CAS registry number)
• InChIKey: Not specified for this item; refer to CoA/Spec Sheet.
• SMILES: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular Formula: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.

Structural features (general/literature description):

• Functional groups: one terminal maleimide ring (activated alkene for Michael addition to thiols); a triethylene glycol (PEG3) spacer; a terminal methoxy cap (–O–CH3) on the distal end.
• Topology: linear triethylene glycol chain providing hydrophilicity and spacing between the maleimide and the payload/biomolecule.
• 2D description in words: a maleimide imide ring connected via an ether linkage to three repeating –CH2–CH2–O– units, ending in a methoxy group.
• Stereochemistry: none (achiral backbone; maleimide is planar, PEG chain is flexible).

Category context:

• Classified under small molecules/compound libraries; commonly used as a heterobifunctional crosslinking/PEGylation reagent for selective thiol coupling.

Synthetic Utility

Functional group logic (general):

• Electrophile: maleimide double bond (activated by imide carbonyls) undergoes Michael addition with thiols rapidly at near-neutral pH, forming a thioether succinimide.
• Spacer: PEG3 imparts water compatibility and spacing without introducing charged groups, useful for tuning solubility and sterics.
• Masked terminus: methoxy cap is inert under typical bioconjugation conditions, serving as a nonreactive handle to prevent crosslinking.

Use cases:

• Bioconjugation: cysteine-directed labeling of proteins/peptides with hydrophilic spacing.
• Material science: installation of short PEG brushes onto thiol-bearing surfaces/nanoparticles to reduce fouling.
• Small-molecule synthesis: incorporation of a PEG3 spacer between a thiol-containing fragment and an inert methoxy terminus to adjust polarity/logS.

Retrosynthetic value:

• Enables convergent assembly: prepare thiol-bearing payloads separately, then couple late-stage under mild conditions with high chemoselectivity.
• Orthogonality: maleimide–thiol coupling is generally orthogonal to amide coupling, click azide–alkyne cycloaddition, and SuFEx, allowing multi-step modular builds.

Analytical cues:

• Reaction progress readily tracked by MS via +[PEG3–maleimide] mass increment on thiol partners; by HPLC, disappearance of maleimide UV band (~300 nm region, literature) may assist monitoring.

Target Specificity

Not applicable. This product is a chemical linker, not a biological targeting reagent or antibody. No antigen, epitope, clone, or species reactivity is specified or implied for this item.