Thermo Scientific Pierce Iodide Beads are 3 mm diameter polystyrene beads coated with oxidizing reagents that enable iodine- Efficient activation of 125 for protein or peptide iodination procedures.

Features of Iodinated Microbeads:

• Derivatized, homogeneous, nonporous polystyrene beads
• Dramatically reproducible iodination
• Iodine-125 Incorporation up to 99%; tagged protein recovery > 90%
• Functions over a wide pH and temperature range
• In the presence of azide, detergents, urea and high salts Iodination
• Efficient iodination of cell membrane surface proteins
• A gentler iodination method than soluble chloramine-T because there is no contact between the protein and the immobilized oxidant (Markwell, 1982)< br>• Fast and easy to use…complete iodination in 2-15 minutes
• Stop the reaction simply by removing the beads from the reaction mixture with tweezers or a Pasteur pipette; no reducing agent is needed to terminate the reaction
• Provides more control over incubation times
• Iodates up to 500 μg of tyrosine-containing peptides or proteins/beads
• Can be used for quantitative iodination of histidine at pH 8.22< br>
Coated iodinated microbeads provide convenient and efficient iodine labeling without the bothersome and oxidative damage effects typically associated with chloramine T and other solution-based methods. One or two microbeads can be added per milliliter of protein solution and then easily removed after the labeling reaction, thereby completely removing the oxidizing reagent from the protein.

Iodination involves the introduction of radioactive iodine into certain amino acids (usually tyrosine) in proteins and peptides. Iodination occurs ortho to the hydroxyl group on tyrosine; mono- or disubstitution may occur. When iodable sites (such as tyrosine) are not present in the protein or the accessibility of these sites is limited, Bolton-Hunter reagents (SHPP and Sulfo-SHPP) can be used to introduce iodable phenolic sites . Some cross-linkers also contain iodatable tyrosyl groups in their spacer arms.

Radioactive 125-I or 131-I can be incorporated into proteins by enzymatic or chemical oxidation. In the chemical oxidation method, sodium iodide is converted into its corresponding reactive iodine form and then spontaneously incorporated into the tyrosyl group. Although oxidizing reagents are necessary for iodine activation, they may damage proteins. Iodinated microbeads (formerly IODO-microbeads) provide a solid phase arrangement that minimizes damaging effects.