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EZ-Link Iodoacetyl-LC-Biotin

Haloacetyl-activated biotinylation reagent for sulfhydryl labeling.

EZ-Link Iodoacetyl-LC-Biotin

Thermo Scientific EZ-Link Iodoacetyl-LC-Biotin is a mid-length, haloacetyl-activated, sulfhydryl-reactive biotinylation reagent that forms stable, irreversible thioether bonds at alkaline pH.

Iodoacetyl-LC-Biotin is a haloacetyl-biotin compound for labeling protein cysteines and other molecules that contain sulfhydryl groups. This reagent specifically reacts with reduced thiols (-SH) in alkaline buffers to form permanent (irreversible) thioether bonds. The unique feature of Iodoacetyl-LC-Biotin is its extended yet chemically simple hexylenediamine spacer arm.


  • Protein labeling – biotinylate antibodies or other proteins for use in protein methods
  • Membrane-permeable – can be used to label inside cells (intracellular)
  • 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
  • Irreversible – forms permanent thioether bonds; spacer arm cannot be cleaved
  • Solubility – must be dissolved in DMSO or DMF before further dilution in aqueous buffers
  • Medium length – spacer arm (total length added to target) is 27.1 angstroms; contains hexylenediamine extension

Product Details:

Chemical structure of Iodoacetyl-LC-Biotin
Chemical structure of Iodoacetyl-LC-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-LC-Biotin. This sulfhydryl-reactive compound whose spacer arm is extended with hexylenediamine.
Alternative names Long-chain (LC) iodoacetyl-biotin
Chemical name N-Iodoacetyl-N-biotinylhexylenediamine
Molecular formula C18H31IN4O3S
Molecular weight 510.43
Spacer arm length 27.1 angstroms
Mass added to target 382.53 daltons
Form White to light yellow powder
Solubility at least 2mg/mL in DMF for subsequent dilution 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.


  • Electron microscopy studies on spatial relationships between proteins (Ref.1)
  • Localizing the SH1 thiol of the myosin head using avidin-biotin complexes in electron microscopy (Ref.2)


  1. Sutoh, K., Yamamoto, K. and Wakabayashi, T. (1984). J. Mol. Biol. 178, 323-339.
  2. Yamamoto, K., Sekine, T. and Sutoh, K. (1984). FEBS 176, 75-78.

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
21333 EZ-Link Iodoacetyl-LC-Biotin
Formulation: Iodoacetyl-activated biotin with a hexylenediamine spacer
Sufficient For: Approx. 25 uses to label a total of 490mg of IgG using typical conditions
50mg Product Instructions for product #21333 EZ-Link Iodoacetyl-LC-Biotin MSDS for product #21333 EZ-Link Iodoacetyl-LC-Biotin Certificate of Analysis for product #21333 EZ-Link Iodoacetyl-LC-Biotin $193.00

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Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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