SCO-PEG3-COOH , CAS No.2141976-36-3

CAS: 2141976-36-3 Cat. No.: S1446819 Fórmula: C₁₈H₂₉NO₇ Peso molecular: 371.43

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Descripción general

SCO-PEG3-COOH is a PROTAC linker and belongs to the PEG class. SCO-PEG3-COOH contains SCO and COOH that can be covalently combined with amino groups respectively. SCO is often used to react with amino acid residues of proteins or peptides , particularly lysine.

Specifications

Condiciones de almacenamiento de almacenamiento

Store at -20°C

Enviado en

Ice chest + Ice pads

Este producto requiere envío en cadena de frío. Los servicios terrestres y otros servicios económicos no están disponibles.

Nombres e identificadores

Peso molecular

371.43

Application Protocols

No vendor-validated protocols are provided for this SKU. The following are general, literature-based procedures to serve as starting points. Optimize for your system.

• Protocol A: SPAAC labeling of an azide-modified protein (general)

  1. Prepare protein at 1–10 mg/mL in PBS (pH 7.4).
  2. Dissolve SCO-PEG3-COOH in dry DMSO to 10–50 mM; add to protein to achieve 2–10 molar equivalents per azide site (final DMSO ≤5%).
  3. Incubate at 20–25°C for 1–4 h (or 4°C overnight for sensitive proteins).
  4. Quench/exchange buffer by desalting (NAP-5) or dialysis; analyze by intact MS and SDS-PAGE.

• Protocol B: Installation of SCO onto an amine-functional surface (EDC/NHS) (general)

  1. Equilibrate amine-functional substrate in 50 mM MES, pH 5.5.
  2. Prepare a 10–50 mM solution of SCO-PEG3-COOH in DMF or DMSO; add to MES (final organic ≤20%).
  3. Add EDC (50–100 mM) and NHS or sulfo-NHS (50–200 mM); activate 15–30 min at RT.
  4. Introduce the substrate; react 1–2 h, then rinse thoroughly.
  5. For capture, incubate with azide-bearing partner in PBS at RT until completion.

• Protocol C: NHS-ester intermediate for peptide coupling (general)

  1. In dry DMF, add NHS (1.2 eq) and EDC (1.2 eq) to SCO-PEG3-COOH (1.0 eq) at 0–5°C; stir 15–30 min.
  2. Add amine-bearing peptide and DIPEA (2–3 eq); stir 1–2 h at RT.
  3. Quench, concentrate, and purify by RP-HPLC.

Note: These protocols are general guidance, not item-specific specifications.

Biological Roles

• Item-specific biological role (from Product Data)

  • None stated. Research use only.

• General context (general chemistry/biochemistry)

  • SCO-PEG3-COOH is not a natural metabolite and has no inherent biological function. It is a synthetic linker used to enable bioorthogonal conjugation in biochemical systems.
  • The strained cyclooctyne participates in SPAAC with azide-functionalized biomolecules (glycans, peptides, proteins, nucleic acids), forming stable triazoles without a metal catalyst. This orthogonality minimizes interference with native biochemical processes during labeling.
  • The PEG3 segment improves aqueous handling, reduces nonspecific hydrophobic interactions relative to non-PEGylated strained alkynes, and can increase linker flexibility between the biomolecule and the conjugated payload.
  • The terminal carboxylate allows standard amide bond formation to amines, enabling site-specific installation of the SCO moiety onto proteins (via lysine side chains), peptides (N-terminus), or amine-functional surfaces.

• Considerations in biological systems (general)

  • Maintain physiological pH (7.0–7.4) for live-cell–compatible workflows; avoid high organic solvent percentages that may perturb membranes or denature proteins.
  • PEG segments can reduce protein adsorption and aggregation; however, short PEGs (PEG3) provide modest stealth compared to long PEG chains.
  • Confirm absence of sodium azide in buffers when quantifying kinetics, but note that SPAAC targets organic azides, not inorganic azide anion.

Buffer Applications

While SCO-PEG3-COOH is not a buffer reagent, its performance depends on appropriate buffer selection for activation and conjugation.

• SPAAC conjugation (general guidance)

  • Buffers: PBS (pH 7.2–7.4), HEPES (pH 7.2–7.5), or Tris (avoid high Tris during EDC activation but compatible for SPAAC).
  • Ionic strength: 100–200 mM total salts are commonly used to maintain protein stability.
  • Co-solvent: 2–10% DMSO or DMF helps dissolve the reagent before dilution into buffer.

• EDC/NHS coupling of the –COOH (general guidance)

  • Preferred buffers: MES (50 mM, pH 5.0–6.5) or phosphate (pH 6.0–7.2). Avoid Tris and other primary amine buffers during activation as they compete with target amines.
  • Additives: NHS (or sulfo-NHS for aqueous systems) to form a more stable active ester; use immediately after formation.

• Practical recipes (non-item-specific)

  • MES buffer: 50 mM MES, 150 mM NaCl, pH 5.5; dissolve SCO-PEG3-COOH in DMSO (10–50 mM), add to buffer (final DMSO ≤10%), add EDC (5–10 mM) and NHS (5–20 mM), incubate 15–30 min, then introduce amine-bearing partner at pH 7.0–7.4.
  • SPAAC: Prepare azide-bearing partner in PBS (pH 7.4), add SCO-PEG3-COOH stock (DMSO) to desired stoichiometry, mix gently at RT; typical reaction times range from 0.5–16 h depending on concentration.

Note: All conditions are literature/general guidance and should be optimized for specific biomolecules.

Green Alternatives

Consider greener aspects across solvent choice, process design, and reagent selection when deploying SCO-PEG3-COOH.

• Solvent selection (greener options; general)

  • Prefer aqueous buffers with minimal DMSO/DMF (≤10%) to reduce VOC burden.
  • Ethanol or isopropanol can sometimes replace acetonitrile for pre-dissolution, subject to solubility testing.

• Reagent alternatives (comparative, literature/general)

  • BCN-PEGn-COOH: bicyclononyne motifs can show similar SPAAC reactivity with potentially improved hydrophobic balance; selection depends on target and solubility needs.
  • DBCO-PEGn-COOH: often higher SPAAC rates but more hydrophobic; may require more organic co-solvent, impacting greenness.
  • Tetrazine–TCO systems (bioorthogonal alternative): extremely fast kinetics but rely on different handles and can be more synthetically intensive.

• Process intensification (general)

  • Use concentrated stocks and micro-scale additions to minimize solvent use.
  • Perform reactions at ambient temperature to reduce energy consumption; SPAAC typically proceeds efficiently without heating.

• Example comparison (general; not item-specific specifications)

  | Option | Rate with azides (relative) | Aqueous compatibility | Notes | |---|---|---|---| | SCO-PEG3-COOH | Medium | Good with co-solvent | Balanced hydrophilicity via PEG3 | | DBCO-PEG3-COOH | Medium–High | Moderate | Often needs more organic cosolvent | | BCN-PEG3-COOH | Medium | Good | Often lower background reactivity |

Tradeoffs: faster systems may increase hydrophobicity or synthetic footprint; PEG length increases aqueous solubility but raises molecular mass and persistence in the environment.

Pharmaceutical Uses

• Item-specific pharmacopeial or excipient status (from Product Data)

  • None provided. This product is labeled For research use only.

• General roles in pharma R&D (non-clinical; no therapeutic claims)

  • Conjugation linker: SCO-PEG3-COOH can be used in discovery research to generate antibody-, protein-, peptide-, or oligonucleotide–conjugates through SPAAC to azide-bearing counterparts.
  • Surface modification: functionalization of device or nanoparticle surfaces with SCO groups for downstream azide capture in formulation studies.
  • Payload installation: enables attachment of small molecules to biomolecules via a two-step sequence (amide coupling of –COOH followed by SPAAC).

• Considerations (general)

  • Regulatory path: not compendial; for any use beyond research, full impurity profiling, residual solvent limits, and extractables/leachables assessments would be required.
  • Stability studies: conduct forced degradation and accelerated stability in intended formulation buffers to define shelf life of working solutions/stocks.
  • Residual copper avoidance: SPAAC avoids Cu(I) catalysts, advantageous for sensitive biologics and reduces metal residual concerns compared to CuAAC.

• Documentation

  • For GMP-related feasibility studies, request detailed CoA, synthetic route summary, and impurity data from the supplier; this listing does not specify these parameters.

Physical Properties

Item-specific physicochemical data are not provided for this SKU.

• Item-specific values (from Product Data)

  • Appearance: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.

• Literature/general expectations for this class (clearly non-specification)

  • Physical state: typically a white to off-white solid for PEG3-linked strained alkynes (literature/general).
  • Solubility (general):
    • High in polar aprotic solvents (DMSO, DMF, acetonitrile) due to PEG segment (literature/general).
    • Moderate in alcohols (MeOH, EtOH) and aqueous buffers when aided by co-solvent or during in situ carboxylate formation (literature/general).
    • Low in nonpolar hydrocarbons (literature/general).
  • Ionization: terminal –COOH pKa for simple PEGylated benzoic acids is typically ~4–5; for aliphatic carboxylates ~4–5 (literature/general). Actual pKa for this specific item is Not specified; refer to CoA/Spec Sheet.
  • Partitioning: PEG3 reduces hydrophobicity vs. plain SCO; overall amphiphilic behavior (literature/general).
  • Stability: strained cyclooctynes are generally stable solids; avoid strong nucleophiles or prolonged basic conditions that can induce side reactions (literature/general).

• Handling implications (general)

  • Hygroscopic tendency can be moderate due to PEG; store tightly closed in dry conditions to preserve accurate mass and performance (general guidance).

Quality and Grades

• Item-specific quality information (from Product Data)

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

• Interpreting common grades for this class (general guidance)

  • Research or synthetic grade SCO-PEG reagents are typically supplied at ≥95% purity by HPLC or NMR, with documentation of residual solvents and water content on the CoA (literature/general). Because no grade is listed here, users should consult the CoA for acceptance criteria and impurity profile.
  • For bioconjugation, low levels of acid, base, and metallic residues are important to avoid side reactions with biomolecules; vendors often provide LC–MS purity and water content by Karl Fischer (general expectations only, not specifications).

• Stabilizers/additives

  • No stabilizer is listed for this item. If a stabilizer is present, it will be disclosed on the CoA/Spec Sheet. In general, SCO reagents are shipped neat without inhibitors (general note).

• What to verify upon receipt (practical tips)

  • Check the CoA for purity, residual solvents, and identity confirmation (NMR, LC–MS).
  • Confirm mass balance after desiccation if the material appears hygroscopic.
  • For bioconjugation applications, run a small-scale test coupling to verify performance with your specific buffers and co-solvents.

Reaction and Applications

SCO-PEG3-COOH is engineered for orthogonal bioconjugation and materials functionalization, providing a copper-free click handle (SCO) and a carboxyl group for coupling chemistry.

• Key reaction families (general/literature)

  • Strain-Promoted Azide–Alkyne Cycloaddition (SPAAC): rapid, catalyst-free cycloaddition with organic or biomolecular azides to form stable triazoles. Compatible with physiological buffers and live-cell–compatible workflows (literature/general).
  • Carbodiimide-mediated amide coupling: activation of the –COOH with EDC (± NHS) to form amide bonds to primary amines on peptides, proteins, or surfaces (literature/general).
  • Active ester intermediates: in situ NHS ester formation for one-pot activation/conjugation sequences.
  • Solid/materials functionalization: immobilization on amine-functional resins, nanoparticles, or polymers to furnish SCO-presenting surfaces for subsequent azide capture.

• Selectivity and orthogonality (general)

  • SCO selectively reacts with azides in complex biological matrices; minimal cross-reactivity with thiols or amines compared to maleimides or NHS esters.

• Practical considerations (general)

  • Maintain neutral pH for SPAAC (6.5–8.0) to preserve biomolecule integrity and SCO stability.
  • For EDC/NHS activation, control pH 5.0–7.0 to balance activation rate and hydrolysis; promptly proceed to coupling.
  • Use minimal organic co-solvent to avoid protein denaturation; 2–10% DMSO is commonly tolerated in many systems.

• Typical outcomes (general)

  • Formation of a non-reducible triazole linkage via SPAAC, offering high stability to hydrolysis and redox conditions, suitable for robust conjugates and surface coatings.

Reaction Conditions

The following conditions are general literature guidance for SCO-type reagents and should be optimized experimentally for this specific item.

• SPAAC with azides (general)

  • Solvent: PBS or HEPES (pH 7.0–7.4) with 0–10% DMSO.
  • Temperature: 20–25°C (ambient). Lower temperatures slow kinetics; mild heating (up to 37°C) can accelerate but assess biomolecule stability.
  • Concentration: 10–500 µM typical for biomolecule conjugations; higher for surface functionalization.
  • Stoichiometry: 1.2–5.0 equivalents SCO relative to azide-bearing biomolecule sites to drive completion.
  • Time: 0.5–16 h depending on concentrations and sterics.

• EDC/NHS activation and amide coupling (general)

  • Activation buffer: MES (50 mM), pH 5.0–6.5; optional 0.1 M NaCl to stabilize proteins.
  • Reagents: EDC 1.1–5.0 equiv; NHS or sulfo-NHS 1.1–10 equiv relative to –COOH.
  • Temperature: 0–25°C; lower temperatures reduce hydrolysis during activation.
  • Activation time: 10–30 min; then adjust pH to 7.0–7.4 and add amine partner.
  • Organic co-solvent: 2–20% DMF/DMSO as needed for solubility; minimize for sensitive biomolecules.

• Purification (general)

  • Small molecules: silica gel chromatography (avoid strong base on column); or reversed-phase HPLC.
  • Bioconjugates: desalting columns, dialysis (MWCO per construct), or preparative SEC/RP-HPLC.

• Analytical monitoring (general)

  • LC–MS for small molecules; SDS-PAGE and intact protein MS for protein conjugates; UV/Vis or fluorescence if payloads permit.

Safety and Handling

Safety information provided here is general guidance. Always consult the product’s SDS for authoritative instructions.

• Item-specific hazard statements (from Product Data)

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

• General safety profile (general chemistry knowledge)

  • Likely hazards: organic carboxylic acids and PEGylated strained alkynes are commonly classified as irritants; avoid inhalation of dust and skin/eye contact.
  • Peroxide formation: not expected (no ether solvent functionality susceptible to autoxidation; polymeric PEG segment does not typically form hazardous peroxides under storage).
  • Reactivity: SCO undergoes strain-promoted azide–alkyne cycloaddition (SPAAC) with azides; avoid unintended exposure to azide-containing materials if preservation of the SCO handle is critical.

• PPE and engineering controls (good practice)

  • Wear safety glasses, lab coat, and appropriate chemically resistant gloves (e.g., nitrile). Work in a fume hood when weighing or dissolving.

• First-aid overview (general)

  • Skin/eye contact: rinse with water for 15 minutes; remove contaminated clothing; seek medical attention if irritation persists.
  • Inhalation: move to fresh air; seek medical attention if symptoms occur.
  • Ingestion: rinse mouth; do not induce vomiting; seek medical attention.

• Storage incompatibilities (general)

  • Avoid strong bases and strong nucleophiles for prolonged times (may degrade SCO). Protect from moisture to prevent hydrolysis-driven impurities and maintain accurate concentration.

Solvent Selection

SCO-PEG3-COOH is amphiphilic: a hydrophilic PEG3 terminus and a hydrophobic strained alkyne. This profile informs dissolution and reaction media.

• Polarity and miscibility (general)

  • Polar aprotic solvents (DMSO, DMF, acetonitrile) typically provide excellent solubility and stability of the SCO moiety.
  • Alcohols (MeOH, EtOH) offer moderate solubility; use when subsequent aqueous dilution is required.
  • Aqueous buffers: limited intrinsic solubility as the free acid; solubility increases in mildly basic media (carboxylate form) or with co-solvents (5–20% DMSO/DMF).

• Typical use scenarios (general)

  • SPAAC bioconjugation: PBS or HEPES buffer, pH 7.0–7.4, often with ≤10% DMSO as a co-solvent to pre-dissolve the reagent.
  • Amide coupling (EDC/NHS): MES or phosphate buffer (pH 5.0–7.0) with DMF/DMSO cosolvent for dissolving the SCO-PEG3-COOH prior to activation.

• Comparison to alternatives (general)

  • DBCO analogs: more hydrophobic; may require higher organic content than PEGylated SCO derivatives.
  • Longer PEG linkers (PEG4–PEG12): improve aqueous solubility but may increase molecular size and alter biomolecule properties.

• Practical tips

  • Pre-make a concentrated stock (e.g., 10–50 mM) in anhydrous DMSO; aliquot and freeze to minimize freeze–thaw cycles.
  • Filter stocks (0.22 µm PTFE) if particulates are present; avoid cellulose esters due to potential adsorption of hydrophobic moieties.

Storage and Reconstitution

• Item-specific storage and shipping (from Product Data)

  • Storage Conditions: Store at -20°C.
  • Shipped In: Ice chest + Ice pads.

• General storage guidance for this class

  • Protect from moisture and light; store in the original, tightly capped container under inert atmosphere if available (desiccant recommended) to minimize PEG-associated hygroscopic uptake.
  • Allow vial to equilibrate to room temperature in a desiccator before opening to avoid condensation.

• Reconstitution (general guidance; not item-specific specifications)

  • Prepare concentrated stocks in anhydrous DMSO or DMF (e.g., 10–50 mM). Vortex to dissolve fully; gentle warming (≤30°C) may assist.
  • For aqueous use, dilute stocks into buffer immediately before use. Maintain final organic content as low as compatible with the system (typically ≤10%).
  • For EDC/NHS activation in water, consider using sulfo-NHS and keep activation times short to limit hydrolysis.

• Aliquoting and stability (general)

  • Aliquot stock solutions into single-use portions; store at -20°C to -80°C. Avoid repeated freeze–thaw cycles.
  • Monitor performance periodically (e.g., LC–MS for intact mass) if solutions are stored >1–2 weeks.

• Disposal

  • Dispose of waste solutions and contaminated materials in accordance with institutional and local regulations for organic chemical waste.

Structure and Identity

Brief overview: SCO-PEG3-COOH is a bifunctional bioconjugation building block combining a strained cyclooctyne (SCO) for copper-free click chemistry with a short triethylene glycol (PEG3) spacer terminating in a carboxylic acid.

• Item-specific identifiers (from Product Data)

  • SKU: S1446819
  • Product Name: SCO-PEG3-COOH
  • CAS: 2141976-36-3
  • Molecular Formula: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular Weight: Not specified for this item; refer to CoA/Spec Sheet.
  • SMILES: Not specified for this item; refer to CoA/Spec Sheet.
  • InChIKey: Not specified for this item; refer to CoA/Spec Sheet.

• Structural features (general chemistry knowledge)

  • Functional groups: strained cyclooctyne (internal alkyne embedded in an eight-membered ring), ether linkages (–O–CH2–CH2–O–)×3 comprising PEG3, and a terminal carboxylic acid (–COOH).
  • Topology: SCO ring connected via a PEG3 spacer to a terminal –COOH; overall amphiphilic character due to hydrophobic SCO and hydrophilic PEG.
  • Stereochemistry: SCO motifs may possess conformational bias due to ring strain; no defined stereocenters are typically present unless substituted asymmetrically (general note).
  • 2D description in words: an eight-membered cyclic alkyne (SCO) on one end, linked by three ethylene glycol units to a terminal carboxyl group, forming a linear spacer between a click-reactive handle and a coupling handle.

• Category Path (from Product Data): 全部 / 可售 / 小分子和化合物库

• Research use note (from Product Data): For research use only

Synthetic Utility

SCO-PEG3-COOH is a modular synthon combining two orthogonal handles, enabling convergent assembly of complex constructs.

• Functional group reactivity (general)

  • –COOH: amenable to activation (EDC/HOBt, EDC/NHS, T3P, SOCl2) and coupling to primary/secondary amines, alcohols (esterification), or hydrazides.
  • SCO alkyne: participates in SPAAC with organic azides to furnish triazoles; orthogonal to most nucleophiles and electrophiles used in peptide/oligo chemistry.
  • PEG3 spacer: imparts flexibility and hydrophilicity, often improving solubility and reducing steric hindrance during coupling steps.

• Named/standard transformations (literature/general)

  • SPAAC bioconjugation (Bertozzi-type copper-free click).
  • NHS-ester intermediates for aqueous-phase amide formation.
  • Mixed anhydride or acid chloride formation for non-aqueous coupling where necessary.

• Retrosynthetic value (general)

  • Enables stepwise installation: first anchor the linker to the scaffold via amide bond formation, then perform azide capture via SPAAC.
  • Facilitates library synthesis: parallel conjugation to diverse azide-bearing payloads without metal catalysts, streamlining purification.

• Practical notes

  • Control activation stoichiometry to minimize O→N acyl transfer and hydrolysis.
  • When modifying proteins, consider targeting exposed lysines or N-termini; assess site distribution by MS to manage heterogeneity.
  • For surfaces, pre-functionalize with amines (APTES on silica, EDA on polymers), then couple via EDC/NHS to present SCO groups densely.

Target Specificity

This product is a small-molecule linker, not a biological targeting reagent or antibody.

• Item-specific data from Product Data: none provided.
• Applicability: Target specificity (antigen/epitope, clone, isotype, species reactivity) is not applicable to SCO-PEG3-COOH.

For selectivity in chemistry, refer to Reaction & Applications, where the SCO moiety displays chemical selectivity toward azides via SPAAC (general chemistry knowledge).