H2N-PEG5-Hydrazide , CAS No.H1444861

CAS: H1444861 Cat. No.: H1444861 Formula: C₁₃H₂₉N₃O₆ Molecular Weight: 323.39

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Overview

H2N-PEG5-Hydrazide is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs.

Specifications

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

This product requires cold chain shipping. Ground and other economy services are not available.

Names and Identifiers

Molecular Weight

323.39

Application Protocols

No item-specific, vendor-validated protocols are provided for this listing. Below are general, literature-based workflows to help plan experiments; adjust to your system.

A. Hydrazide coupling to oxidized glycoproteins (literature example):

• Oxidize glycans: Treat glycoprotein (e.g., 1–5 mg/mL) with 1–5 mM NaIO4 in 50 mM acetate buffer, pH 5.5, on ice for 15–30 min in the dark. Quench excess periodate (e.g., with ethylene glycol), then desalt.
• Conjugation: Mix oxidized protein with H2N-PEG5-Hydrazide (1.5–10 equiv per aldehyde) in 50 mM acetate, pH 5.5, optionally 50 mM aniline. React 1–4 h at room temperature.
• Stabilization: Add picoline borane (10–20 mM) or NaBH3CN and incubate 1–2 h. Desalt by spin columns or dialysis.

B. Amide coupling to a carboxylated ligand (aqueous EDC/NHS):

• Activate: Dissolve carboxyl component in 50 mM MES, pH 5.5–6.0. Add EDC (1–2 equiv) and NHS (2–5 equiv); stir 10–20 min.
• Couple: Add H2N-PEG5-Hydrazide (1–3 equiv relative to carboxyls). React 1–2 h at room temperature.
• Quench/purify: Add hydroxylamine or dilute buffer to quench; purify by dialysis or HPLC.

Notes:

• Avoid amine-containing buffers during activation/coupling.
• Verify conjugation by MS or electrophoresis (for proteins).
• These steps are general guidance only; optimize stoichiometry, pH, and time for your substrates.

Biological Roles

This product is a synthetic bifunctional linker supplied for research use only; it is not a natural metabolite and has no intrinsic biological role assigned.

General biochemistry context (literature/informational):

• PEGylation concept: PEG chains are widely used to improve aqueous solubility, reduce nonspecific interactions, and provide a flexible spacer between a biomolecule and a tag or surface. The PEG5 length offers a short hydrophilic tether that can mitigate steric hindrance during binding or catalysis studies.
• Carbonyl targeting via hydrazide: Hydrazide groups react with aldehydes/ketones generated on biomolecules, especially on oxidized glycans (e.g., on glycoproteins and cell surfaces), enabling enrichment, labeling, or immobilization without directly modifying amino acid side chains.
• Orthogonal functionalization: The terminal amine enables subsequent (or prior) amide coupling to carboxyl-bearing biomolecules, probes, or polymers, supporting modular assembly of conjugates.

Use cases in biochemical research (examples without clinical claims):

• Preparation of enzyme–polymer conjugates for stability studies.
• Immobilization of oxidized glycoproteins on hydrazide-functional supports for glycomics workflows.
• Installation of hydrophilic spacers between ligands and reporter groups to tune avidity and reduce aggregation in binding assays.

Note: Any biological testing should be performed under appropriate approvals and containment; no claims are made regarding safety or efficacy in vivo.

Buffer Applications

While H2N-PEG5-Hydrazide is not itself a buffering agent, it is commonly used in specific buffer systems that support its ligation chemistry.

Hydrazone ligation buffers (literature guidance):

• Acetate buffer, pH 4.5–6.0 (50–100 mM): Promotes condensation of hydrazides with aldehydes/ketones. Optional 10–100 mM aniline as a nucleophilic catalyst to accelerate imine formation.
• MES buffer, pH 5.5–6.5 (50–100 mM): Alternative to acetate with low UV absorbance near 214–280 nm.
• Post-ligation reduction: Perform in the same buffer or switch to phosphate-buffered saline (PBS) at pH 6.5–7.4 before adding a mild reducing agent (e.g., picoline borane) to stabilize hydrazones.

Amide coupling in aqueous media:

• EDC/NHS activation often uses MES or phosphate buffers in the pH 4.5–7.4 range; avoid Tris or primary amine-containing buffers which quench activation.

Practical tips:

• Desalt/clean oxidized biomolecules to remove aldehyde-quenching species (e.g., free amines) prior to hydrazide coupling.
• Maintain ionic strength (~0.1–0.3 M NaCl) to reduce nonspecific interactions during protein conjugations.
• For sensitive proteins, consider brief reactions at 4–10 °C with extended times to preserve activity.

Note: Recipes and pH ranges are general literature guidance; optimize for your substrate and workflow.

Green Alternatives

PEG-based linkers are generally viewed as more benign than many hydrophobic crosslinkers due to high water solubility and low volatility. Nonetheless, greener choices also involve solvent and reagent selection.

Greener considerations (literature/general):

• Solvent choices: Favor water or water–ethanol systems for hydrazone ligations when possible. Minimize DMF/DMSO usage or replace with glycerol carbonate, Cyrene, or 2-MeTHF co-solvents where compatible.
• Catalysis: Use organocatalysts (e.g., aniline) at minimal effective loadings; avoid heavy metals.
• Reductive stabilization: Picoline borane is a less hazardous alternative to NaBH3CN in many reductive amination protocols.
• Energy: Ambient-temperature ligations reduce energy consumption; mild heating (≤37 °C) only if necessary.

Comparison (informational):

• Conventional approach: DMF/DMSO as solvents; EDC/NHS for amide coupling; NaBH3CN for hydrazone reduction.
• Greener alternative: Aqueous acetate/MES buffers; water-soluble carbodiimides with minimal organic cosolvent; picoline borane for reduction; ethanol/water systems when solubility permits.

Trade-offs:

• Reaction rate vs. solvent greenness: Purely aqueous systems may slow kinetics; small amounts of DMSO (≤10–20%) can restore rates with minor environmental impact.
• Stability: Hydrazones are acid-sensitive; greener conditions may still require a reduction step for long-term stability.

Note: Select alternatives based on the compatibility of biomolecules/materials and required performance.

Pharmaceutical Uses

This product is provided for research use only and is not intended for human or veterinary use.

Informational context (non-clinical, literature):

• Formulation development and analytics: Short PEG linkers like PEG5 are employed in preclinical research to explore PEGylation effects on solubility, aggregation, and surface presentation of ligands or peptides. The hydrazide end can capture aldehyde-bearing analytes for immobilization in analytical devices.
• Conjugate prototyping: The amine terminus enables rapid amide coupling to model actives or excipients (e.g., carboxylated polymers) to prototype PEGylated conjugates for physicochemical characterization (e.g., size, charge, binding in vitro).
• Device/surface modification: Hydrophilic tethering layers for biosensor surfaces, allowing oriented immobilization of oxidized glycans or carbohydrate ligands while minimizing nonspecific adsorption due to the PEG spacer.

Regulatory/status notes:

• No pharmacopeial monograph is indicated for this specific bifunctional PEG; quality attributes (purity, residual solvents, endotoxin/bioburden) must be established per application. Not specified for this item; refer to CoA/Spec Sheet.
• For any work towards cGMP or clinical applications, source GMP-grade materials with full traceability and validated analytics; this listing does not state such compliance.

Physical Properties

Item-specific numerical specifications are not provided for this catalog entry. Refer to the CoA/Spec Sheet for definitive values.

Item-specific (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.

General/literature characteristics for PEG5 diamine/hydrazide linkers (informational, not item specifications):

• Physical state: typically a white to off-white solid or viscous gum; strongly hygroscopic due to PEG ether oxygens and terminal polar groups.
• Solubility: highly soluble in water and polar organic solvents (e.g., DMSO, DMF, methanol); limited solubility in nonpolar solvents (hexanes, toluene) due to PEG polarity.
• pKa (qualitative): terminal primary amine is basic (conjugate acid pKa typically ~9–10, literature); hydrazide NH groups are weakly acidic and nucleophilic; exact values vary with local structure.
• Partitioning: PEG chains are hydrophilic; overall low logP and good miscibility with aqueous media (literature).
• Thermal behavior: PEGylated linkers often exhibit broad, ill-defined melting transitions and may soften before melting; decomposition may precede boiling under ambient pressure (literature observation).
• Hygroscopicity: tends to absorb atmospheric moisture; handling in a dry environment is recommended to maintain accurate massing and to minimize hydrolysis/contamination.

Note: For precise data (e.g., MW of the PEG5 variant, water content, residual solvents, or UV cutoff), consult the item’s CoA/SDS.

Quality & Grades

Item-specific grade/purity are not provided in the Product Data.

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

Context and guidance (informational):

• Research grade: Most PEG linkers for R&D are supplied at high chemical purity suitable for synthesis and bioconjugation. If HPLC-grade or >95% purity is required for sensitive applications (e.g., quantitative bioconjugation), confirm by CoA.
• Low-residuals: For bioconjugation, low residual solvents, low inorganic salts, and accurate MW distribution are important. If needed, request data on water content (KF), residual solvents (GC), and metal content (ICP). Not specified for this item; refer to CoA/Spec Sheet.
• Stabilizers: PEG linkers typically do not require stabilizers; however, some vendors add trace acid scavengers or antioxidants. None are specified here.
• Analytical verification: Identity and purity are commonly supported by 1H/13C NMR, HRMS/ESI-MS, and HPLC/UPLC. If you require specific analytical methods or acceptance criteria (e.g., % area by HPLC, endotoxin/bioburden for bio-related uses), consult the CoA or request a detailed specification sheet.

Note: This listing does not state GMP compliance; material is for research use only.

Reaction & Applications

This bifunctional linker is engineered for convergent and orthogonal bioconjugation.

Key application domains (literature/general guidance):

• Carbonyl-selective ligation: The hydrazide end reacts chemoselectively with aldehydes/ketones (e.g., on oxidized glycans from periodate-treated glycoproteins) to give hydrazones. The linkage can be stabilized by reductive amination (NaBH3CN/picoline borane) to a secondary amine.
• Amide coupling: The terminal amine couples to activated carboxylic acids (NHS esters, acid chlorides) or via carbodiimides (EDC/NHS) to introduce the PEG spacer onto carboxyl-bearing molecules, surfaces, or polymers.
• Surface and material modification: Grafting to carboxylated nanoparticles, resins, or films to present hydrazide groups for subsequent capture of carbonyl-functional ligands, or vice versa.
• Protein and carbohydrate conjugation: Site-selective labeling via aldehydes introduced by mild periodate oxidation of sialic acid/diol-containing glycans; PEG spacer reduces steric hindrance and improves solubility.
• Sequential/orthogonal strategies: The amine can be protected (e.g., Boc/Fmoc) to enable selective hydrazide reactions, then deprotected for a second coupling step.

Practical tips:

• For hydrazone formation, mildly acidic pH (4.5–6) and aniline catalysts can significantly accelerate rates; subsequent reduction improves stability.
• For amide couplings in organic media, dry conditions and excess coupling reagent (HATU/HBTU) help drive completion; in water, EDC/NHS is effective near pH 4.5–7.4.
• Purification: Dialysis or ultrafiltration for bioconjugates; preparative HPLC or SEC for small-molecule conjugates.

Note: Optimize stoichiometry to minimize crosslinking in protein work; typically 1.1–5 equiv of linker per reactive handle depending on target density.

Reaction Conditions

Guidance below reflects common literature practice for bifunctional PEG amine–hydrazide linkers and should be optimized per substrate; these are not product specifications.

Hydrazone formation (with aldehydes/ketones):

• Buffer: 50–100 mM sodium acetate or MES, pH ~4.5–6.0; optional 10–100 mM aniline catalyst.
• Concentrations: 0.1–10 mM linker depending on substrate density; higher for surface immobilization.
• Temperature/time: Room temperature for 1–4 h; colder temperatures extend times; gentle agitation improves mass transfer.
• Stabilization: Reduce hydrazones in situ or post-reaction using picoline borane or sodium cyanoborohydride under mildly acidic to neutral pH.

Amide coupling via amine terminus:

• Organic phase: DMF or DCM with HATU/HBTU (1.1–1.5 equiv) and DIPEA (2–4 equiv); 0.01–0.1 M substrate concentration; room temperature to slight warming; typical reaction times 0.5–4 h (literature).
• Aqueous phase: EDC (1–2 equiv) with NHS (1–3 equiv) in MES or phosphate buffer (pH 4.5–7.4). Avoid amine-containing buffers (e.g., Tris).

Workup and purification:

• Bioconjugates: Desalting columns, dialysis, or centrifugal filtration (MWCO chosen per target).
• Small-molecule conjugates: Preparative HPLC, SEC, or SPE cleanup. PEGs can elute late on RP HPLC; use gradients and volatile buffers.

Yields (literature ranges):

• Hydrazone ligations often proceed to high conversion; isolated yields depend on purification strategy and can vary widely (50–90%).
• Amide couplings under optimized conditions commonly afford good to excellent yields (>70%).

Analytical control: Monitor by LC–MS, MALDI (for biomolecules), and UV at 214/280 nm where applicable.

Safety & Handling

Authoritative safety information should be obtained from the product-specific SDS.

Item-specific hazard data (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/pictograms: Not specified for this item; refer to SDS.

General safety guidance for PEGylated amine/hydrazide linkers (informational):

• Likely hazards: PEG backbones are generally of low acute toxicity, but terminal functional groups can be irritants. Hydrazides can cause skin/eye irritation and may be harmful if swallowed or inhaled; avoid aerosol formation. Treat as a laboratory chemical of unknown toxicity.
• PPE: laboratory coat, safety glasses, and appropriate chemically resistant gloves (e.g., nitrile). Use in a fume hood to avoid inhalation of dusts or vapors from solutions.
• First aid overview: In case of skin contact, wash with soap and water; for eye contact, rinse cautiously with water for several minutes and seek medical attention; if inhaled, move to fresh air; if ingested, rinse mouth and seek medical attention. Follow SDS instructions.
• Storage incompatibilities: Avoid strong oxidizers and strong acids/bases that can degrade PEG chains or hydrazide functionality. Avoid reactive acylating agents unless intended for coupling.
• Stability considerations: Hydrazides can slowly hydrolyze or oxidize in aqueous/oxygenated environments; prepare fresh solutions when possible and minimize exposure to air/moisture. PEG materials may form peroxides only in rare cases compared to ethers like THF; nonetheless, store away from light and heat.
• Waste: Collect aqueous/organic waste according to institutional and regulatory guidelines; do not dispose to drain.

Solvent Selection

H2N-PEG5-Hydrazide is a highly polar, hydrophilic linker. Solvent choice should prioritize solubility, reaction compatibility with amines/hydrazides, and downstream purification.

General/literature guidance (not item specifications):

• Aqueous systems: Freely soluble in water, PBS, and common bioconjugation buffers. For hydrazone ligations, mildly acidic buffers (acetate, MES, pH ~4.5–6) are typical; for amide couplings via the amine, neutral to slightly basic buffers are preferred when using water-soluble carbodiimides.
• Polar aprotic: DMSO and DMF provide excellent solubility for synthetic couplings (HATU/HBTU, EDC/NHS). Mixtures with water can balance reactivity and solubility for biomolecule labeling.
• Alcohols: Methanol/ethanol are suitable for stock solutions but may interfere with some coupling reagents; confirm compatibility.
• Nonpolar solvents: Poorly soluble in hydrocarbons or chlorinated nonpolars; not recommended unless used as minor co-solvents.

When to choose alternatives:

• If purely aqueous, amine-reactive NHS esters of PEG may offer faster kinetics for protein labeling than in situ EDC couplings.
• For carbonyl-targeted ligations at neutral pH, consider aminooxy analogs (oxime formation) over hydrazides; they can display faster kinetics in some settings.

Small comparison (literature-based):

• Hydrazide vs aminooxy: Hydrazides are broadly available and stable; aminooxy groups often react faster with aldehydes/ketones at near-neutral pH but can be more sensitive to oxidation.

Storage & Reconstitution

Item-specific storage from Product Data:

• Storage conditions: Store at −20 °C.
• Shipped in: Ice chest + Ice pads.

General handling guidance (informational):

• Hygroscopicity: PEG linkers readily absorb moisture. Store tightly sealed under dry conditions (desiccant) to maintain integrity and accurate massing.
• Light/air: Protect from prolonged exposure to air and light. If possible, blanket opened containers with inert gas (e.g., nitrogen) before re-sealing.

Reconstitution and stock solutions:

• Solvents: Water, buffer (as appropriate for application), or polar organics such as DMSO/DMF. Filter sterilize (0.22 μm) if sterility is required for biochemical work.
• Concentration: Prepare concentrated stocks (e.g., 10–100 mM in DMSO or water, as solubility permits) and aliquot to minimize freeze–thaw cycles.
• Storage of solutions: Short-term at 2–8 °C; for longer-term, freeze aliquots at −20 °C or below. Avoid repeated freeze–thaw; discard if turbidity or precipitation appears.

Stability notes (literature):

• Hydrazide functionality can slowly hydrolyze or oxidize in aqueous solution; prepare fresh solutions before critical conjugations.
• For prolonged storage, keep as a dry solid at −20 °C; bring to room temperature in a desiccator before opening to prevent condensation.

Research Use Note: For research use only.

Structure & Identity

H2N-PEG5-Hydrazide is a bifunctional polyethylene glycol (PEG) linker bearing a terminal primary amine on one end and a terminal hydrazide on the other, separated by five ethylene glycol (–CH2–CH2–O–) repeat units. This architecture provides high aqueous solubility, flexibility, and a defined spacer length for bioconjugation.

• SKU: H1444861
• Product name: H2N-PEG5-Hydrazide
• CAS: H1444861 (catalog identifier provided)
• 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/literature description):

• Functional groups: primary amine (–NH2), hydrazide (–CONHNH2), and multiple ether linkages (PEG chain).
• Spacer: five oxyethylene units provide a hydrophilic, flexible, ~2–3 nm reach in fully extended conformations (qualitative, literature).
• 2D description in words: A linear PEG chain of five –O–CH2–CH2– segments terminated on one end by –NH2 and on the other by –C(=O)–NH–NH2. No stereocenters; achiral and conformationally flexible.
• Conjugation handles: amine for amide coupling to activated carboxyls (e.g., NHS esters); hydrazide for chemoselective condensation with aldehydes/ketones to give hydrazones (and optionally reduced to stable secondary amines).

Synthetic Utility

H2N-PEG5-Hydrazide is a versatile building block for modular assembly of conjugates, enabling orthogonal transformations at each terminus.

Key functional group reactivity (literature):

• Primary amine: Forms amides with activated carboxylic acids (NHS esters, mixed anhydrides, acid chlorides). Carbodiimide-mediated coupling (EDC/NHS) allows aqueous operations. The amine can also undergo urea/thiourea formation with isocyanates/isothiocyanates and sulfonamide formation with sulfonyl chlorides.
• Hydrazide: Chemoselective condensation with aldehydes/ketones to yield hydrazones; subsequent reduction affords stable C–N bonds (reductive amination). Hydrazides also acylate to form acyl hydrazides and can capture acyl imidazoles.
• PEG chain: Inert spacer that improves solubility and reduces aggregation; resists many reaction conditions, but strong acids/bases and dehydrating agents can cleave or depolymerize PEG under forcing conditions.

Strategic uses:

• Convergent assembly: Attach the amine end to a carboxyl-functional component; later, ligate the hydrazide to a carbonyl-bearing partner, minimizing protecting-group gymnastics.
• Protection/orthogonality: Temporary protection of the amine (Boc/Fmoc) allows selective hydrazide chemistry without competitive amine reactions.
• Biorthogonal staging: Combine with periodate-oxidized glycans for site-selective immobilization; reduction step locks the linkage.

Workbench tips:

• Control stoichiometry to prevent overfunctionalization/crosslinking.
• Employ mild bases (DIPEA) for amide couplings in organic media; avoid nucleophilic buffers (e.g., Tris) during EDC/NHS activations.

Target Specificity

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

• Antigen/epitope: Not applicable.
• Species reactivity/clone/isotype: Not applicable.
• Any target-binding properties arise only after conjugation to a targeting ligand designed by the end user.