IODO-BEADS

IODO-BEADS Containing N-Chlorobenzenesulfonamide Groups on a Polystyrene Backbone... 

Figure 12.4 IODO-BEADS contains immobilized chloramine-T groups that can react with radioactive iodide in...

Lee, D.S.C., and Criffiths, B.W. (1984) Comparative studies of Iodo-Bead and chloramine-T methods for the radioiodination of human alpha-fetoprotein./. Immunol. Meth. 74, 181-189. 

The radioiodination procedure (see Note 9) described here uses IODO-BEADS, which contain the sodium salt of IV-chloro-benzenesulfonamide immobilized on nonporous, polystyrene beads. Immobilization of the oxidizing agent allows for easy separation of the latter from the reaction mixture. This method also prevents the use of reducing agents. 

Wash 6-8 IODO-BEADS twice with 5 mL of PBS Dry the beads by rolling them on a clean filter paper... 

Markwell (1982) reported that the reaction mechanism for creating the electrophilic iodine species may be somewhat different for IODO-BEADS than other oxidizing agents. She demonstrated that the active component remained at or near the... 

IODO-BEADS may be used in a variety of buffer salts and in the presence of detergents or denaturants without affecting iodination. The reagent, however, is susceptible to inactivation by reducing agents such as disulfide reductants, and it can be inactivated by moisture on storage. Also avoid organic solvents that can dissolve or affect the surface characteristics of polystyrene, such as DMF or DMSO. 

Figure 265 IODO-BEADS contains immobilized Chloramine-T functional groups that can react with radioactive iodide in aqueous solution to form a highly reactive intermediate. The active species may be an iodosulfonamide derivative, which then can iodinate tyrosine or histidine residues in proteins.

IODO-BEADS reaction from the manufacturer s recommended pH 7.0 to 8.2 (Tsomides et al., 1991). No reducing agent is required to stop the iodination reaction, as is the case with chloramine-T and other methods. Simple removal of the bead(s) from the reaction is enough to eliminate the iodination process. The mild nature of the IODO-BEADS iodination reaction can result in better recovery of active protein than using soluble oxidants (Lee and Griffiths, 1984). 

Wash one or more IODO-BEADS (Pierce) with the iodination buffer of choice. Buffers containing 0.1 M sodium phosphate or 0.1 M Tris at slightly acidic to slightly alkaline pH work well. A buffer consisting of 0.1 M sodium phosphate, pH 6.5, will give the highest possible reaction rates and yields. 

IODO-GEN (Pierce), first described by Fraker and Speck in 1978, is 1,3,4,6-tetrachloro-3a,6a-diphenylglycouril, an N-haloamine derivative with oxidizing properties similar to those of IODO-BEADS and chloramine-T. The compound is insoluble in aqueous solution, therefore making it a type of solid-phase radioiodination reagent. However, unlike IODO-BEADS, wherein the oxidizing group is immobilized on an-... 

Cheng H, Rudick MJ (1991) A membrane blotting method for following the time course of protein radioiodination background references using IODO-BEADS, Anal Biochem 198 191-193... 

Use iodogen-coated tubes for radioiodination of streptavidin and b-catalase. The iodo-beads technique, described in the recommendations of the manufacturer (Pierce) is also suitable and offers similar results. 

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