Mal-PEG-mal (MW 3400) , CAS No.M1445670

CAS: M1445670 Cat. No.: M1445670 Peso molecolare: 3400(Average)

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Panoramica

Mal-PEG-mal (MW 3400) is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs.

Specifications

Condizioni di conservazione di stoccaggio

Store at -20°C

Spedito in

Ice chest + Ice pads

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Nomi e identificatori

Peso molecolare

3400(Average)

Application Protocols

No item-specific, tested application protocols are provided for this product. Refer to your internal SOPs and relevant literature for protocol development tailored to your substrates and scale.

Notes

• This reagent is intended for research use only.
• For guidance on general conditions, see the Reaction Conditions tab.

Biological Roles

This product is a synthetic polymer linker intended for research use; it does not have inherent biological activity. Relevant biological context concerns how the reagent interfaces with biomolecules during conjugation.

• PEG backbone (literature/general)

  • Poly(ethylene glycol) is widely used to impart hydrophilicity, reduce nonspecific protein adsorption, and improve colloidal stability of biomaterials. It is generally considered biologically inert and nonionic.

• Maleimide end groups

  • Highly selective for thiol-bearing residues (e.g., cysteine in proteins, thiolated oligonucleotides/peptides) at near-neutral pH, enabling site-specific conjugation and crosslinking.

• Bioconjugation implications

  • Installation of PEG spacers can modulate hydrodynamic size, reduce aggregation, and space functional ligands from surfaces or cores. Bifunctional maleimide enables inter- or intramolecular bridging of thiol sites, including protein cyclization.

• Metabolic fate

  • As a research reagent, metabolic and in vivo roles are not applicable here. Any downstream biological interactions depend entirely on the conjugation partners and application design.

For research use only; not intended for diagnostic or therapeutic use.

Buffer Applications

While Mal-PEG-mal is not itself a buffering reagent, buffer choice is critical for successful thiol–maleimide conjugation.

• Recommended buffers for conjugation (literature/general)

  • Phosphate or HEPES, pH 6.5–7.2: Maximizes thiol selectivity and minimizes maleimide hydrolysis and amine competition.
  • Citrate/phosphate at pH ~6.0–6.5 for very sensitive thiols, trading some rate for selectivity.
  • Ionic strength: 50–150 mM salt typical for proteins; adjust to maintain solubility and stability of partners.

• Buffers/agents to avoid

  • Reducing agents with free thiols (DTT, β-mercaptoethanol): Consume maleimide and interfere with conjugation.
  • High pH (>8) buffers: Accelerate hydrolysis and can promote undesired amine addition.
  • Excess imidazole and other nucleophiles can compete at elevated pH.

• Compatibility notes

  • TCEP is generally compatible for disulfide reduction; remove excess via desalting before adding Mal-PEG-mal.
  • Tris buffer at neutral pH is usually acceptable, but avoid basic conditions.

• Practical recipe hints (general)

  • Prepare 10× phosphate buffer (0.5–1.0 M, pH 7.0), dilute to 50–100 mM final; degas if oxidation is a concern.
  • Prepare Mal-PEG-mal stocks in anhydrous DMSO or water immediately before use; add slowly to buffered thiol solution with mixing.

All item-specific buffer specs are not provided; consult your SOPs and the CoA for any special instructions.

Green Alternatives

Maleimide–thiol coupling is already advantageous from a green chemistry perspective: it proceeds rapidly in water at ambient temperature without metals or added catalysts. Nonetheless, alternative chemistries may be preferred depending on lifecycle and selectivity needs.

• Comparison of linker chemistries (literature/general)

| Chemistry | Typical solvent | Catalysts/metals | Selectivity | Notes | |---|---|---|---|---| | Maleimide–thiol (this product) | Aqueous buffers | None | Cys/thiol selective at pH 6.5–7.5 | Fast, water-based; maleimide hydrolysis is a waste stream consideration | | Vinyl sulfone–thiol | Aqueous buffers | None | Thiol selective over broad pH | More hydrolytically robust; slower than maleimide | | NHS ester–amine | Aqueous buffers | None | Lys/amine selective | Competes with hydrolysis; less site-selective on proteins | | SPAAC (azide–DBCO) | Aqueous buffers | None (Cu-free) | Bioorthogonal | Requires azide/DBCO installation; excellent in complex media | | CuAAC (azide–alkyne) | Aqueous/EtOH | Cu(I) | Bioorthogonal | Copper waste and potential cytotoxicity; very robust click linkage |

• Greener practice with Mal-PEG-mal

  • Favor water or HEPES/PBS, avoid high-boiling polar aprotics when possible.
  • Prepare concentrated stocks to minimize solvent usage; quench and dispose of hydrolyzed residues per local regulations.
  • Plan stoichiometry to reduce excess electrophile and unreacted thiol, lowering downstream purification burden.

• Tradeoffs

  • Maleimide chemistry maximizes speed/efficiency but is moisture/pH sensitive. Vinyl sulfone PEG linkers offer improved stability at the cost of slower kinetics. SPAAC is extremely selective but increases molecular mass and cost.

Pharmaceutical Uses

No pharmacopeial status or excipient grade is provided for this item; refer to the CoA/Spec Sheet for any compliance details. Content below describes general research/formulation roles for similar materials and should not be interpreted as clinical guidance.

• Research formulation roles (literature/general)

  • Bioconjugation/PEGylation: Bifunctional maleimide PEGs can bridge cysteine sites within or between biomolecules, enabling controlled dimerization, cyclization, or multimer formation for research evaluation.
  • Biomaterials: Crosslinker for forming hydrogels and coatings under mild, aqueous conditions without added catalysts or metals, useful in prototype drug delivery matrices and in vitro models.
  • Spacer/stealthing: PEG segments reduce nonspecific interactions and can serve as hydrophilic spacers between active moieties and carriers in experimental formulations.

• Manufacturing considerations

  • Solvent and residual control: For any work approaching regulated environments, verify residual solvents, bioburden, endotoxin, and metal content on a batch CoA.
  • Process robustness: Maleimide groups are base/moisture sensitive; process under controlled humidity and neutral pH to preserve functionality.

For research use only. No therapeutic, diagnostic, or clinical claims are made for this product.

Physical Properties

Item-specific physical specifications are not provided in the product data. Refer to the CoA/Spec Sheet for authoritative values.

• Provided values

  • Molecular weight (average): ~3400 g/mol (item-specific nominal average)
  • Other physical properties: Not specified for this item; refer to CoA/Spec Sheet.

• Typical properties for PEG-based Mal-PEG-mal (literature/general)

  • Physical state: Solid at ambient temperature; PEGs in this MW range are typically waxy/solid.
  • Solubility: Highly soluble in water and many polar organic solvents (e.g., PBS, HEPES buffer, DMF, DMSO). Maleimide functionality remains most selective in near-neutral, aqueous buffers.
  • Hygroscopicity: PEGs can be hygroscopic; maleimide groups are moisture- and base-sensitive (hydrolyze to maleamic acids), so minimize exposure to humidity.
  • pKa/logP: Not applicable as a polymer; overall behavior is nonionic and hydrophilic.
  • Viscosity: Aqueous solutions above ~5–10 wt% can become noticeably viscous (literature generalization for PEG 3–5 kDa).

• Handling implications

  • Prepare solutions immediately before use to limit maleimide hydrolysis.
  • Use degassed buffers when coupling to thiol-sensitive biomolecules to limit oxidative disulfide re-formation.

All numerical specifications (mp, bp, density, RI, water content, residual solvents, UV cutoff) are not specified for this item; refer to CoA/Spec Sheet.

Quality and Grades

• Item-specific grade/purity: Not specified for this item; refer to CoA/Spec Sheet.

• How to interpret quality for PEG linkers (general guidance)

  • Average molecular weight and polydispersity (Đ): PEGs are inherently polydisperse; reputable suppliers report an average MW and often Đ by GPC/SEC. Lower Đ improves batch-to-batch consistency in crosslinking and gelation kinetics.
  • Functional end-group integrity: Degree of substitution (DOS) and intact maleimide content are critical. Typical analytical controls include 1H NMR (maleimide vinylic signals), UV assay for maleimide, and titration with a model thiol.
  • Residual impurities: Monomeric PEGs, solvent residues, and hydrolyzed maleamic acid can reduce performance. CoA typically lists residual solvents and water content; request these if needed for sensitive applications.
  • Bioconjugation suitability: For protein work, low bioburden, low endotoxin, and trace-metals screening may be relevant. If these are critical, confirm with the specific CoA/spec sheet.

• Stabilization/handling implications

  • Maleimide hydrolysis is the main degradation pathway; cold, dry storage slows this. Some suppliers nitrogen-pack PEG-maleimides; if provided, maintain inert atmosphere during storage/use.

• Documentation

  • For regulatory or QC-sensitive workflows, request batch CoA detailing average MW method (e.g., GPC vs MALDI), DOS, residuals, and assays of free maleimide.

Reaction and Applications

This reagent is a homobifunctional thiol-reactive crosslinker useful across bioconjugation, polymer chemistry, and materials assembly.

• Core reaction (literature/general)

  • Maleimide–thiol Michael addition: Rapid, chemoselective formation of stable thioether bonds at pH ~6.5–7.5 without added catalysts. Reaction proceeds via conjugate addition of a thiolate to the maleimide double bond.

• Application areas

  • Protein–protein and protein–polymer crosslinking: Inter- or intramolecular linking of cysteine residues for dimerization, cyclization, or PEGylation strategies.
  • Hydrogel formation: Step-growth crosslinking with thiol-terminated PEGs, peptides, or polymers to yield biocompatible networks with tunable mechanics and degradation via embedded cleavable motifs.
  • Surface and nanoparticle modification: Immobilization of thiol-bearing ligands on maleimide-functionalized surfaces or reciprocal assembly by reacting Mal-PEG-mal with thiolated surfaces to introduce PEG spacing.
  • Small-molecule assembly: Bridging two thiol-containing molecules to generate defined bis-thioether products.

• Practical tips

  • Maintain pH 6.5–7.2 for highest selectivity over amines; above pH 8, competing amine addition and maleimide ring opening increase.
  • Reduce disulfides with TCEP, then remove excess reductant (desalt) before adding Mal-PEG-mal. Avoid DTT/βME carryover.
  • Use slight molar excess of maleimide over free thiol; monitor progress by Ellman’s assay or LC/MS of the thiol partner.
  • Minimize time of Mal-PEG-mal in aqueous solution prior to use; prepare fresh.

• Post-reaction stability

  • Thioether–maleimide linkages are generally stable; retro-Michael exchange can occur in the presence of excess thiol at elevated pH—mitigated by ring hydrolysis to succinimide thioether or by subsequent stabilization strategies.

Reaction Conditions

General guidance for thiol–maleimide conjugation with Mal-PEG-mal (literature-based; optimize per system):

• Typical conditions

  • pH: 6.5–7.2 in phosphate or HEPES buffer; selectivity for thiols is maximal in this range.
  • Temperature: 20–25°C; lower temperatures slow hydrolysis and can be used for sensitive proteins. Reactions often complete in 15–120 minutes.
  • Stoichiometry: 1.1–2.0 equivalents of maleimide per free thiol. For bifunctional crosslinking, balance stoichiometry to control network formation vs discrete bridging.
  • Concentration: 0.1–10 mM in reactive groups; higher concentrations accelerate gelation in hydrogel formation.
  • Solvent: Aqueous buffer; optional cosolvent (≤10–20% v/v DMSO or DMF) for solubility.

• Reducing conditions

  • Reduce disulfides with TCEP (0.5–5 mM) at pH ~7, 15–60 min, then desalt to remove excess reductant prior to adding Mal-PEG-mal. Avoid DTT/βME carryover.

• Quenching and workup

  • Quench unreacted maleimide with an excess of a low-molecular-weight thiol after the desired coupling is complete, or allow controlled hydrolysis at pH ~8 if appropriate.
  • Purify conjugates by SEC for proteins or precipitation/dialysis for polymers and hydrogels.

• Expected performance

  • High conversions are typical under neutral pH without catalysts. Side reactions (amine addition, hydrolysis, retro-Michael) increase above pH 8 and with prolonged reaction times.

These conditions are general literature guidance, not item-specific specifications.

Safety and Handling

Safety classifications for this specific item are not provided in the product data. Always consult the product SDS for definitive information.

• GHS information (item-specific)

  • Signal word: Not specified for this item; refer to SDS.
  • Pictograms: Not specified for this item; refer to SDS.
  • Hazard statements: Not specified for this item; refer to SDS.
  • Classification: Not specified for this item; refer to SDS.

• General hazards for maleimide-terminated PEGs (literature/general)

  • Maleimides are electrophilic and can react with thiols; avoid skin/eye contact. May cause irritation or sensitization in susceptible individuals.
  • PEG backbone is generally considered of low acute toxicity, but end-group reactivity governs handling.

• PPE and lab practices

  • Wear safety glasses, lab coat, and appropriate chemical-resistant gloves (e.g., nitrile). Work in a fume hood when weighing and during solution preparation.
  • Avoid inhalation of dust/aerosols; prevent contact with skin and eyes.

• Incompatibilities and stability

  • Avoid strong bases and prolonged exposure to pH > 8 (maleimide ring hydrolysis to maleamic acid reduces thiol reactivity).
  • Avoid free thiol reducing agents (DTT, β-mercaptoethanol) in buffers prior to conjugation; TCEP is generally compatible but use minimal excess and remove after reduction.
  • Moisture and heat accelerate hydrolysis; keep cold and dry.

• First-aid overview (general)

  • Skin/eye contact: Rinse with water for at least 15 minutes; remove contaminated clothing. Seek medical attention if irritation persists.
  • Inhalation/ingestion: Move to fresh air; rinse mouth with water; seek medical advice.

For research use only.

Solvent Selection

Mal-PEG-mal (MW 3400) is a hydrophilic, water-compatible, bifunctional linker. Solvent choice should protect maleimide integrity while maximizing solubility and maintaining thiol selectivity.

• Polarity and miscibility (literature/general)

  • Highly polar, freely miscible with water; soluble in polar aprotic solvents (DMSO, DMF, NMP) and many buffered aqueous systems (PBS, phosphate, HEPES).
  • Limited solubility in nonpolar solvents.

• Practical selection guidance

  • Aqueous conjugations: Use degassed PBS or phosphate/HEPES at pH 6.5–7.2 to maximize thiol selectivity and minimize hydrolysis.
  • Organic media: For water-sensitive substrates, anhydrous DMSO or DMF stocks (e.g., 10–100 mM) can be prepared and diluted into buffer immediately before use.
  • Avoid: Strongly basic buffers (pH > 8) and buffers containing free thiols (DTT, βME). Tris and other amine buffers are generally acceptable at neutral pH but avoid high pH where maleimides can slowly react with amines.

• Small comparison (general)

  • Water/PBS: Green, biocompatible, best for proteins; fastest hydrolysis if left for long periods.
  • HEPES (pH 6.8–7.2): Good buffering near optimal pH; minimal nucleophilicity.
  • DMSO/DMF: Excellent solubilizers; keep anhydrous; limit exposure time before dilution to buffer.

Select solvent based on substrate solubility, reaction kinetics, and sensitivity of thiol-bearing partners.

Storage and Reconstitution

• Item-specific storage and shipping

  • Storage conditions: Store at -20°C (per product data). Keep container tightly closed under dry, inert atmosphere if possible.
  • Shipped in: Ice chest + ice pads (per product data).

• Stability and handling (general)

  • Protect from moisture and prolonged exposure to elevated temperature or basic pH to preserve maleimide functionality.
  • Allow container to equilibrate to room temperature before opening to avoid condensation.

• Reconstitution/preparation (general guidance)

  • Prepare fresh solutions immediately before use. Dissolve in:
    • Aqueous buffer (phosphate or HEPES, pH 6.5–7.2) for direct conjugations.
    • Anhydrous DMSO or DMF to make concentrated stocks (e.g., 10–100 mM), then dilute into buffer just prior to reaction.
  • Filter sterilize (0.22 μm) if sterility is required for biomolecule work; avoid extended residence time in aqueous media.

• Aliquoting and freeze–thaw

  • Aliquot solids or stock solutions to single-use portions to minimize freeze–thaw and moisture ingress. Store frozen stocks at -20°C; avoid repeated thaw cycles.

• Shelf life

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

For research use only. Always refer to the SDS and lot-specific CoA for definitive handling and stability information.

Structure and Identity

Mal-PEG-mal (MW 3400) is a homobifunctional polyethylene glycol linker bearing maleimide groups at both termini.

• Item-specific identifiers

  • SKU: M1445670
  • Product name: Mal-PEG-mal (MW 3400)
  • CAS: Not specified for this item; refer to CoA/Spec Sheet.
  • 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.
  • Average molecular weight: ~3400 g/mol (item-specific nominal average)

• Structural features (general/literature description)

  • Backbone: Linear polyethylene glycol, repeating unit –CH2–CH2–O–.
  • End groups: Two maleimide rings (highly selective Michael acceptors for thiols) at the α and ω termini.
  • Architecture: α,ω-difunctional PEG; expected to be polydisperse (typical for PEGs) with an average degree of polymerization n ≈ 75–80 for MW ≈ 3400 (literature estimate: 3400/44 ≈ 77).
  • Functional groups: Imide (maleimide), ether oxygens along PEG chain.
  • Appearance: Not specified for this item; refer to CoA/Spec Sheet.

• 2D structure in words

  • A flexible poly(ethylene oxide) chain with a maleimide ring attached via a linker at each terminus: Maleimide–(O–CH2–CH2)n–O–Maleimide.

Notes: Exact composition and end-group structures for PEG reagents are averages; consult the specific CoA for polydispersity (Đ), substitution, and identity data.

Synthetic Utility

Mal-PEG-mal (MW 3400) is a versatile α,ω-bifunctional electrophile enabling modular assembly of macromolecules and small molecules under mild conditions.

• Functional group reactivity (literature/general)

  • Two terminal maleimides act as soft Michael acceptors for thiols, forming stable thioether bonds. Selectivity is high at pH 6.5–7.5 and can be leveraged for step-growth polymerizations or discrete conjugations.

• Use cases

  • Macrocyclization: Intramolecularly bridge two cysteine residues on a peptide/protein to stabilize conformation.
  • Dimerization/multimerization: Intermolecularly link two thiol-bearing molecules to create defined dimers or networks.
  • Network formation: Crosslink thiol-terminated PEGs, peptides, or polysaccharides to form hydrogels. Mechanical properties can be tuned through stoichiometry, concentration, and MW.
  • Surface passivation: React with thiolated surfaces (e.g., gold–thiol SAMs) to introduce PEG spacers terminated with maleimide for subsequent ligation, or conversely consume both maleimides to bridge two surfaces.

• Retrosynthetic perspective

  • Treat Mal-PEG-mal as a length-defined, hydrophilic spacer connecting two thiol-derived nodes. The PEG segment imparts flexibility and water compatibility, decoupling reactive sites and reducing steric hindrance around biomacromolecules.

• Analytical and process notes

  • Monitor conversion by disappearance of free thiols (Ellman’s) and/or shift in SEC/MALS for macromolecular assemblies.
  • Control equivalents carefully to avoid gelation when discrete conjugates are desired.

Target Specificity

Not applicable. This product is a chemical crosslinker, not a biological targeting reagent or antibody. No antigen/epitope specificity, clone, isotype, or species reactivity data are associated with this item.

Domande frequenti

How should this product be stored?

Store at ?20 °C. Freezer storage is required to maintain the specified shelf life.

How is this product shipped?

This product ships in an insulated container with ice pads. Unpack on arrival and transfer it to the storage condition stated above.

What are the CAS number, molecular formula and molecular weight?

The CAS Number is M1445670, and the molecular weight is 3400(Average) g/mol.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.