Description
5-Iodoacetamidofluorescein (5-IAAF) – Thiol-Reactive Fluorescein for Cysteine and Thiol-Modified Oligo Labeling
5-Iodoacetamidofluorescein (5-IAAF) is a highly efficient thiol-reactive fluorescent dye, ideal for covalent labeling of cysteine residues in proteins or thiol-modified oligonucleotides. It features an iodoacetamide reactive group that forms a stable thioether linkage with sulfhydryl groups, enabling precise and reliable bioconjugation.
With strong absorption at 492 nm and fluorescence emission at 513 nm, 5-IAAF provides bright and sensitive detection in biochemical assays, structural biology, and fluorescence imaging. The compound is supplied as a yellow solid and is readily soluble in DMF for derivatization protocols.
Performance Highlights
-
Specific and efficient thiol labeling via iodoacetamide-thiol chemistry
-
Bright green fluorescence (Ex/Em: 492 nm / 513 nm)
-
Forms stable thioether bonds with cysteines and thiol-modified DNA/RNA
-
Suitable for bioconjugation in protein and oligonucleotide workflows
-
Optimal fluorescence in T&S buffer, pH 9
Properties
-
CAS Number: 63368-54-7
-
Molecular Weight: 538.27
-
Empirical Formula: C₂₄H₁₃NO₆I
-
Absorption [λmax]: 492 ± 3 nm
-
Emission [λmax]: 513 ± 3 nm
-
Extinction Coefficient (ε): >70,000 M⁻¹·cm⁻¹
-
Reactive Moiety: Iodoacetamide (reacts with thiols to form thioether linkages)
-
Solubility: DMF
-
Appearance: Yellow powder
-
Storage: −20 °C, dry, protected from light (especially in solution)
-
Fluorescence Reading Buffer: T&S Buffer, pH 9
-
Chemical Name: 2-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)-5-(2-iodo-acetylamino)-benzoic acid
Applications
-
Site-specific labeling of proteins via cysteine residues
-
Bioconjugation of thiol-modified oligonucleotides
-
Fluorescence detection in biochemical and structural assays
-
Preparation of custom probes and fluorophore-tagged biomolecules
