OPSS-PEG-COOH - MW 10000 Da

Cat. No.: O164097

GRADE & PURITY MW 10000 Da

Storage

Room temperature

Shipped In

Normal

Visão geral

Ortho-pyridyl disulfide (OPSS) functionalized polyethylene glycol (OPSS PEG) is a thiol (-SH) group reactive PEG derivative that can be used to modify biomolecules or other materials via their available thiol groups. Ortho-pyridyl disulfide reacts with thiol group to form a stable disulfide bond while a thiol pyridyl group is released.

Specifications

Especificações e pureza

MW 10000 Da

Condições de armazenamento de armazenamento

Room temperature

Enviado em

Normal

Propriedades químicas e físicas

• Solubilidade: Off-white/white solid or viscous liquid depends on molecule weight;Soluble in regular aqeous solution as well as most organic solvents

Application Protocols

The following general protocols are provided as literature‑based examples to guide use; they are not item‑specific validated methods.

A. Installing OPSS handle on an amine‑bearing surface (two‑step EDC/NHS then thiol capture)

1. Dissolve OPSS‑PEG‑COOH at 5–20 mg/mL in dry DMSO. Separately prepare 100 mM MES, pH 5.5.
2. Activate: Mix linker with EDC (10–50 mM final) and NHS (equimolar) in MES; incubate 15–20 min at RT.
3. Apply to the amine‑functional surface or polymer in pH 7.2 phosphate buffer for 1–2 h.
4. Rinse; quench residual NHS esters with 50 mM ethanolamine, 10 min.
5. Introduce thiol‑bearing ligand (protein/peptide with free –SH) in HEPES pH 7.2, 0.5–2 h. Monitor A343–354 nm for 2‑thiopyridone release.

B. Direct conjugation to a cysteine‑containing protein

1. Generate free thiols selectively (e.g., TCEP treatment), then remove reductant by desalting.
2. Prepare OPSS‑PEG‑COOH stock in DMSO (10–50 mM). Add to protein in phosphate buffer pH 7.2 to achieve 1.2–2.0 molar eq per accessible cysteine; keep final DMSO ≤10%.
3. React 1 h at RT with gentle mixing; monitor by UV at ~343 nm and confirm by MS.
4. Purify conjugate by size‑exclusion chromatography; collect fractions by UV at 280 nm and verify absence of pyridinethione.

C. Reductive release (optional)

• Incubate conjugate with 5–10 mM GSH or 1–10 mM DTT in PBS, pH 7.4, for 0.5–2 h at RT; remove reductant and analyze release.

Adjust concentrations and times to the specific PEG MW and substrate.

Biological Roles

This product is a synthetic linker and does not have inherent biological roles in metabolism. However, its components influence biological interfacing in research settings (general/literature perspective):

• PEG segment: Hydrophilic, flexible, and protein‑repellent. PEGylation can reduce nonspecific binding and aggregation, and modulate hydrodynamic size and surface hydration of biomaterials.
• OPSS end group: Enables selective conjugation to accessible thiols (e.g., cysteinyl residues) under mild, near‑physiological conditions. The disulfide formed is cleavable in reducing environments, enabling reversible attachment in studies of intracellular trafficking or redox‑responsive materials.
• Carboxyl end: Provides a route to install the linker onto amine‑bearing targets via EDC/NHS chemistry, allowing construction of heterobifunctional architectures with controlled orientation.

Notes:

• No medical or clinical claims are made; this reagent is for research use only.
• The balance between stability and cleavability of the disulfide bond should be considered for biological assays: extracellular milieu is typically oxidizing, while intracellular cytosol is more reducing (literature), enabling stimulus‑responsive behavior.
• OPSS by‑product 2‑thiopyridone has a characteristic UV band near 343–354 nm (literature) and can be tracked during conjugation to confirm reaction progress without modifying the biological target.

Buffer Applications

While OPSS‑PEG‑COOH is not a classical buffer, successful use in bioconjugation depends critically on buffer composition and pH. The following are general, literature‑based recommendations:

• Thiol–disulfide exchange (OPSS coupling to –SH):

  • Buffer: Phosphate or HEPES, 20–100 mM, pH 7.0–7.5; 50–150 mM NaCl to maintain ionic strength.
  • Additives: 0.1–1 mM EDTA to chelate trace metals that can catalyze thiol oxidation.
  • Avoid: Primary amines at high concentrations (do not directly interfere with OPSS, but can complicate sequential EDC/NHS workflows); avoid reducing agents (DTT, β‑ME) during the OPSS coupling step.

• Carboxyl activation (EDC/NHS):

  • Activation buffer: MES, 50–100 mM, pH 4.5–6.0 (optimal stability for O‑acylisourea/NHS esters).
  • Coupling buffer: Phosphate or HEPES, pH 7.2–7.4 for amide formation with primary amines.
  • Quenching unreacted NHS esters: Ethanolamine (10–50 mM) in the coupling buffer post‑reaction.

• Stock solutions:

  • Prepare OPSS‑PEG‑COOH stocks in dry DMSO or DMF and dilute into buffer immediately before use to minimize hydrolysis or side reactions.

Always degas buffers for thiol chemistry and filter‑sterilize if working with proteins. Optimize concentrations and pH for specific substrates.

Green Alternatives

Greener practice with OPSS‑PEG‑COOH focuses on solvent selection, aqueous processing, and minimizing auxiliary reagents, since the linker chemistry itself is fixed by the OPSS and carboxyl functionality.

Strategies (literature/general):

• Prefer aqueous buffers for both EDC/NHS activation (MES, pH 5–6) and thiol–disulfide exchange (phosphate/HEPES, pH 7–7.5), adding minimal DMSO/DMF only if solubility demands.
• Use TCEP selectively and sparingly for thiol generation (it is odorless and more handling‑friendly than DTT); remove by desalting before OPSS coupling to avoid premature reduction.
• Replace chlorinated solvents with ethanol/water or acetate buffer systems for washing and processing where feasible.

Comparison of linker choices (general; pros/cons relative to OPSS):

• OPSS vs maleimide end group:
  • OPSS: reversible disulfide bond (cleavable), UV‑traceable via 2‑thiopyridone; slower kinetics than maleimide; less sensitive to hydrolysis than maleimide at neutral pH.
  • Maleimide: faster Michael addition at pH 6.5–7.0; forms thioether (non‑cleavable) but can undergo ring‑opening/retro‑Michael under some conditions; more hydrolysis‑prone in alkaline solution.
• OPSS vs vinylsulfone:
  • Vinylsulfone: robust thioether formation, broader pH window; requires longer times; non‑cleavable.

Trade‑offs: Selecting OPSS enables reductive release (useful for circular economy of supports or controlled release) but introduces sulfur‑containing by‑products that require appropriate waste handling. Aqueous workflows reduce solvent burden and improve EHS profile.

Pharmaceutical Uses

No pharmacopeial status or excipient grade is specified for this item. This product is offered for research use only.

General formulation/manufacturing context (literature):

• As a research‑grade PEG linker, OPSS‑PEG‑COOH is used to prototype redox‑cleavable conjugates and surfaces, e.g., attaching payloads to polymers, proteins, or nanoparticles via disulfide bonds while anchoring the other end through amide linkages.
• PEGylated surfaces prepared with OPSS‑PEG‑COOH can reduce nonspecific protein adsorption in analytical devices and early development assays.
• Process considerations: Control moisture and pH during activation/coupling; thoroughly remove 2‑thiopyridone by‑product by diafiltration or chromatography to meet analytical purity targets in preclinical material preparation.

If an application requires GMP or pharmacopeial compliance, verify availability of appropriate grades, impurity profiles, and documentation. In absence of item‑specific certification details, treat this product strictly as non‑GMP research material.

Physical Properties

Item-specific physicochemical constants are not provided for this catalog entry and can depend on the PEG chain length.

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Exact molecular weight, formula, and polydispersity: Not specified for this item; refer to CoA/Spec Sheet.
• Storage conditions (from Product Data): Room temperature; shipped under normal conditions.

General/literature characteristics for OPSS‑terminated PEGs (indicative, not item‑specific):

• Physical state: typically off‑white solids or viscous oils depending on MW; glass transition observed for higher MW PEGs.
• Solubility: PEGs are highly soluble in water and polar organic solvents (e.g., methanol, ethanol, acetonitrile, DMF, DMSO); OPSS adds an aromatic moiety but usually does not impair aqueous solubility for moderate n. Solubility can decrease in nonpolar solvents.
• pKa: terminal –COOH typically shows aqueous pKa around 4–5 (literature, for aliphatic carboxylic acids); effective acidity can be modulated by neighboring ether oxygens.
• UV properties: OPSS reagents release 2‑thiopyridone upon thiol exchange, which exhibits an absorption band near 343–354 nm (literature) enabling reaction monitoring.
• Viscosity: increases with MW and concentration; PEG solutions display non‑ideal viscosity behavior useful for process considerations.

Note: Do not treat the above as specifications. For batch‑specific values (e.g., average MW, residual solvents, water content), consult the Certificate of Analysis.

Quality and Grades

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

Context and implications for this product class:

• PEG linker quality attributes (general):
  • Average MW and polydispersity (Đ) of the PEG backbone influence solubility, spacing, and conjugation stoichiometry.
  • Functionalization efficiency at both termini (OPSS and COOH) determines active content. Vendors often report substitution >90–95% (literature typical), but item‑specific values are not provided here.
  • Residual solvents, water content, and trace metal levels can impact sensitive bioconjugations; check the CoA for acceptance limits when available.
• Stabilizers: Not specified for this item; refer to CoA/Spec Sheet. Many OPSS reagents are supplied without stabilizer and protected from light; avoid prolonged exposure to basic vapors.
• What to verify before use:
  • Batch‑specific average MW and functional group assay (e.g., OPSS activity via A343 of released 2‑thiopyridone; acid value titration for –COOH).
  • UV/Vis baseline to ensure no pre‑liberated pyridinethione.
  • Moisture content if using in anhydrous coupling chemistry.

If chromatographic applications or bio‑interfacing are intended, choose a grade with low UV background and high end‑group fidelity. For exact specifications, defer to the product’s CoA/SDS.

Reaction and Applications

OPSS‑PEG‑COOH is designed for orthogonal, two‑stage conjugation: thiol‑selective coupling via the OPSS end and amide formation via the carboxyl end. The resulting disulfide linkage is cleavable under reducing conditions, enabling controlled release or reversible attachment.

Key application families (literature/generic):

• Thiol‑selective bioconjugation:
  • Mechanism: thiol–disulfide exchange with cysteine residues forms a disulfide bond to the target and liberates 2‑thiopyridone (A343–354 nm), allowing real‑time monitoring.
  • Use cases: protein PEGylation, antibody fragment or peptide linkage, nanoparticle surface functionalization through surface –SH.
• Carboxyl activation and amide coupling:
  • Use EDC/NHS to activate –COOH, then couple to primary amines on biomolecules or surfaces, installing the OPSS handle for a subsequent thiol‑specific step.
• Surface passivation and spacing:
  • PEG reduces nonspecific adsorption; heterobifunctionality allows directional immobilization on biosensor chips, polymers, or inorganic supports.
• Cleavable linkers in delivery research:
  • Disulfide stability extracellularly and cleavage under intracellular reducing conditions (e.g., glutathione) enables release of cargos in reductive environments.

Practical tips:

• Keep OPSS away from free thiols and strong reductants until the conjugation step. Degas buffers to limit disulfide scrambling.
• Monitor reaction progress by measuring released 2‑thiopyridone at ~343 nm (literature). Quantify substitution via UV and mass balance.
• For protein work, reduce selectively (e.g., TCEP post‑removal) to generate free –SH without over‑reducing native disulfides when site‑selectivity is needed.

Reaction Conditions

Guidance below reflects common literature practices for OPSS‑ and –COOH–functional PEGs and should be optimized per system. These are not item‑specific specifications.

• OPSS–thiol coupling (to cysteines or surface –SH):

  • Buffer: 50 mM phosphate or HEPES, pH 7.0–7.5; 100 mM NaCl; 0.5–1 mM EDTA.
  • Temperature/time: Room temperature, 0.5–4 h; longer for sterically hindered targets.
  • Stoichiometry: 1.1–2.0 eq OPSS‑PEG‑COOH per thiol site (adjust for accessibility).
  • Monitoring: Measure A343–354 nm for released 2‑thiopyridone (literature ε ≈ 8,000 M−1 cm−1 near 343 nm) to estimate conversion; confirm by MS or functional assays.

• EDC/NHS activation of –COOH and amide coupling:

  • Activation: 5–20 mM EDC with equimolar or slight excess NHS in 50–100 mM MES, pH 4.5–6.0, 10–30 min at RT.
  • Coupling: Transfer to amine‑containing target in phosphate/HEPES buffer, pH 7.2–7.4, 0.5–2 h at RT (or 4 °C for sensitive proteins).
  • Quench: 10–50 mM ethanolamine to cap residual NHS esters; wash thoroughly.

• Reductive cleavage (if needed for release studies):

  • Reducing agents: DTT or glutathione (GSH) in the low‑millimolar range at pH 7–8; time 0.5–2 h, RT (literature). Remove reductant promptly to protect native disulfides in proteins.

• Solvent assists:

  • For poorly soluble substrates, include 5–20% DMSO/DMF if compatible with biomolecules. Maintain low headspace oxygen and avoid free thiols unless intended.

Always validate with small‑scale trials and analytical characterization.

Safety and Handling

Safety details specific to this item (GHS classification, pictograms, H‑statements) are not provided in the Product Data. Always consult the product SDS for authoritative information and local compliance.

General laboratory handling guidance for OPSS‑PEG conjugation reagents:

• Hazards (general): May cause skin/eye/respiratory irritation. The OPSS group can undergo thiol–disulfide exchange; avoid contact with free thiols and strong reducing agents unless intended.
• PPE: Use lab coat, safety glasses, and appropriate chemically resistant gloves (e.g., nitrile). Handle powders in a fume hood to avoid dust inhalation.
• Incompatibilities: Strong oxidizers (can over‑oxidize sulfur), strong reducing agents (premature cleavage of disulfide), nucleophiles/base in storage solutions (may degrade OPSS), and free thiols (uncontrolled reaction).
• Environmental precautions: Prevent release to drains; collect waste according to institutional procedures for organic/sulfur‑containing chemicals.
• First aid (overview):
  • Skin/eye contact: Rinse with water for several 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.
• Special risks: OPSS reagents are light‑sensitive; protect from light during handling to minimize premature decomposition. Moisture can affect stability and carboxyl activation efficiency.
• Fire safety: PEGs are combustible; use CO2, dry chemical, or foam. Thermal decomposition may release COx and sulfur oxides.

Signal word, H‑statements, and pictograms: Not specified for this item; refer to SDS.

Solvent Selection

OPSS‑PEG‑COOH combines a hydrophilic PEG matrix with a thiol‑reactive aryl disulfide and a carboxyl group. Solvent choice should preserve OPSS integrity and support the intended coupling step.

• Polarity/miscibility (general behavior):

  • Highly soluble in water and polar organics (DMSO, DMF, NMP, methanol, ethanol, isopropanol); limited solubility in nonpolar solvents (hexanes, toluene) increases with higher MW.
  • OPSS is susceptible to nucleophilic/basic degradation; avoid prolonged exposure to strong bases in solution.

• Typical choices by operation:

  • Thiol–disulfide exchange (to cysteines): aqueous buffers at pH ~7.0–7.5 with 0–20% co‑solvent (DMF/DMSO) if needed; deoxygenated buffers can reduce side reactions.
  • EDC/NHS activation of –COOH: MES buffer, pH 4.5–6.0 (aqueous); or anhydrous DMF/DMSO for nonaqueous activation when substrates are poorly water‑soluble.
  • Purification: desalting columns or dialysis in PBS for conjugates; precipitation into cold acetone/ether for polymer intermediates (literature practice).

• When to choose alternatives:

  • For fully aqueous bioconjugation, maintain ionic strength (e.g., 100–150 mM NaCl) to minimize aggregation.
  • If substrates are base‑sensitive, avoid carbonate buffers; use phosphate or HEPES near neutral pH.

Note: Item‑specific solvent restrictions are not provided; ensure solvent dryness and absence of free thiols to preserve OPSS during stock preparation.

Storage and Reconstitution

• Storage conditions (from Product Data): Room temperature; shipped under normal conditions.
• General best practices for this class of reagents:
  • Store tightly sealed, desiccated, and protected from light to preserve OPSS integrity and minimize hydrolysis/oxidation.
  • Avoid exposure to acidic or basic vapors and to free thiols or reducing agents during storage.
• Reconstitution:
  • Prepare stocks freshly in dry, oxygen‑free solvents such as anhydrous DMSO or DMF. Typical working stocks: 10–100 mM depending on PEG MW and application (literature guidance). Filter if needed.
  • For aqueous use, dissolve immediately before the reaction in degassed buffer. Use within the same day for optimal activity.
• Freeze–thaw: If solutions must be stored, aliquot and freeze at −20 °C to avoid repeated freeze–thaw cycles. However, solid‑state storage is preferred.
• Stability: Exact shelf‑life and active content over time are batch‑dependent and not specified for this item; refer to CoA/Spec Sheet and SDS. Check activity by monitoring 2‑thiopyridone release during a small‑scale test reaction before critical experiments.
• Handling after opening: Record first‑open date, keep under inert gas if possible, and include a desiccant in the container to limit moisture ingress.

Research Use Note: For research use only.

Structure and Identity

OPSS-PEG-COOH is a heterobifunctional polyethylene glycol bearing an ortho‑pyridyl disulfide (OPSS) thiol‑reactive end group and a terminal carboxylic acid for carbodiimide coupling. It functions as a cleavable, thiol‑addressable PEGylation linker.

• Item-specific identifiers:

  • SKU: O164097
  • CAS: 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. (Note: PEG products are often offered as nominal MW series.)
  • SMILES / InChIKey: Not specified for this item; refer to CoA/Spec Sheet.

• Structural features (general description; literature):

  • Backbone: Linear poly(ethylene glycol), –[CH2–CH2–O]n–, providing hydrophilicity and spacing.
  • One terminus: OPSS (2‑pyridyldisulfide) group, i.e., –S–S–C5H4N(o‑pyridyl), which undergoes thiol–disulfide exchange to yield a disulfide bond to the target and liberate 2‑thiopyridone.
  • Other terminus: Carboxylic acid (–COOH) suitable for EDC/NHS activation and coupling to primary amines.
  • Functional group set: aryl disulfide, ether repeat units, terminal carboxylate after deprotonation.

• 2D structure (described): a PEG chain with one end capped by an aryl disulfide (pyridyl ring attached through an S–S linkage) and the opposite end terminating in –COOH. No defined stereocenters; polymeric degree (n) determines average MW.

Synthetic Utility

OPSS‑PEG‑COOH serves as a modular, heterobifunctional spacer for constructing complex architectures under mild conditions.

Functional group reactivity (general/literature):

• OPSS terminus:
  • Selective reaction with thiols via disulfide exchange; leaves a cleavable S–S linkage and releases 2‑thiopyridone (UV‑trackable).
  • Compatible with aqueous conditions and many biomolecules; avoid prior exposure to reductants.
• Carboxyl terminus:
  • Activates with EDC/NHS to form amide bonds to primary amines on peptides, proteins, polymers, or surfaces.
  • Can be transformed to other derivatives (acid chloride, activated esters) in strictly anhydrous organic media when appropriate for materials synthesis.

Typical synthetic roles:

• Installing a thiol‑reactive handle on amine‑bearing substrates (e.g., polymers, surfaces) for subsequent capture of cysteine‑containing ligands.
• Building cleavable linkages in hydrogels and polymer–drug conjugates for release studies.
• Creating PEG spacers that modulate distance, flexibility, and hydrophilicity between functional domains in multicomponent constructs.

Design notes:

• Select PEG chain length to tune hydrodynamic spacing and solubility.
• Sequence coupling steps to avoid cross‑reactivity: complete EDC/NHS amide formation on the –COOH end, purify, then perform OPSS–thiol exchange.
• Quantify end‑group loading to ensure stoichiometric accuracy in multi‑valent assemblies.

Target Specificity

Not applicable. This product is a chemical linker and does not possess biological target specificity (no antigen/epitope, clone, isotype, or species reactivity). Specificity arises from chemical selectivity: OPSS reacts with thiols, and the –COOH end can be coupled to primary amines after activation.

Perguntas frequentes

How should this product be stored?

Store at room temperature.

How is this product shipped?

This product ships under standard ambient conditions. No temperature-controlled packaging is required.

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.