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EZ-Link Iodoacetyl-PEG2-Biotin

Haloacetyl-activated, water-soluble biotinylation reagent for sulfhydryls.

EZ-Link Iodoacetyl-PEG2-Biotin

Thermo Scientific EZ-Link Iodoacetyl-PEG2-Biotin is a mid-length, haloacetyl-activated, sulfhydryl-reactive biotinylation reagent that contains a 2-unit ethylene glycol in its spacer arm for increased water-solubility characteristics.

Iodoacetyl-PEG2-Biotin enables simple and efficient biotin labeling of antibodies, cysteine-containing peptides and other thiol-containing molecules. The iodoacetyl group reacts with reduced thiols (sulfhydryl groups, –SH) at alkaline pH to form stable thioether bond. The hydrophilic, 2-unit polyethylene glycol (PEG) spacer arm imparts water solubility that is transferred to the biotinylated molecule, thus reducing aggregation of labeled proteins stored in solution. The PEG segment adds length and flexibility to the spacer arm, minimizing steric hindrance involved with binding to avidin molecules.


  • Protein labeling – biotinylate antibodies or other proteins for use in protein methods
  • Thiol-reactive – reacts with sulfhydryls (-SH), such as the side-chain of cysteine (C)
  • Iodoacetyl-activated – perform reactions in the dark at pH 7.5 to 8.5 in Tris or borate buffer
  • Pegylated – spacer arm contains a hydrophilic, 2-unit, polyethylene glycol (PEG) group
  • Enhances solubility – pegylation imparts water solubility to the biotinylated molecule, helping to prevent aggregation of biotinylated antibodies stored in solution
  • Irreversible – forms permanent thioether bonds; spacer arm cannot be cleaved
  • Solubility – can be dissolved directly in aqueous buffers for labeling reactions
  • Medium length – spacer arm (total length added to target) is 24.7 angstroms

Product Details:

Chemical structure of Iodoacetyl-PEG2-Biotin
Chemical structure of Iodoacetyl-PEG2-Biotin. This biotinylation reagent labels antibodies and other proteins and molecules that contain sulfhydryl groups (e.g., side-chain of cysteine). For more information, see our review of Iodoacetyl Reaction Chemistry.

Properties of Iodoacetyl-PEG2-Biotin. This sulfhydryl-reactive compound whose spacer arm is extended with a 2-unit ethylene glycol chain (polyethylene glycol), which confers water-solubility.
Alternative names pegylated iodoacetyl-biotin
Chemical name (+)-Biotinyl-iodoacetamidyl-3,6-dioxaoctanediamine
Molecular formula C18H31IN4O5S
Molecular weight 542.43
Spacer arm length 24.7 angstroms
Mass added to target 414.19 daltons
Form White to off-white solid
Solubility at least 25mg/mL in water or buffer
Storage conditions 4°C with desiccant, protect from light and moisture
Reactive groups Iodoacetyl, reacts with sulfhydryls at pH 7.5-8.5

We manufacture biotin reagents to ensure the highest possible overall product integrity, consistency and performance for the intended research applications.

Biotinylation reagents differ in reactivity, length, solubility, cell permeability and cleavability. Three types of sulfhydryl-reactive compounds are available: maleimido, iodoacetyl and pyridyldithiol. Iodoacetyl reagents specifically react with sulfhydryl groups (-SH) at pH 8.3 to form permanent thioether bonds.

In proteins, sulfhydryls exist where there are cysteine (C) residues. Cystine disulfide bonds must be reduced to make sulfhydryl groups available for labeling. Hinge-region disulfide bridges of antibodies can be selectively reduced to make functional half-antibodies that can be labeled.


  1. Kim, K., et al. (2001) J. Biol. Chem. 276, 40591-40598.
  2. Muroi, M., et al. (2002) J. Biol. Chem. 277, 42372-42379.

Related Resources:

Biotinylation Reagents Selection Guide
Review of Biotinylation Methods and Applications
Chemistry of Crosslinking (and Labeling Reagents)

Related Products:

All Biotinylation Reagents
Biotin Quantitation Reagents and Kits
Avidin, Streptavidin, NeutrAvidin Affinity Resins

Ordering Information
Product # Description Pkg. Size Instructions MSDS CofA Price
21334 EZ-Link Iodoacetyl-PEG2-Biotin
Formulation: Iodoacetyl-activated biotin with a diethyleneglycol spacer
Sufficient For: Approx. 25 uses to label a total of 461mg of IgG using typical conditions
50mg Product Instructions for product #21334 EZ-Link Iodoacetyl-PEG2-Biotin MSDS for product #21334 EZ-Link Iodoacetyl-PEG2-Biotin Certificate of Analysis for product #21334 EZ-Link Iodoacetyl-PEG2-Biotin $188.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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