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Iodination of Proteins by IPy2BF4, a New Tool in Protein Chemistry

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journal contribution
posted on 16.05.2006 by Gemma Espuña, David Andreu, José Barluenga, Xavier Pérez, Antoni Planas, Gemma Arsequell, Gregorio Valencia
Iodination is a very useful method for protein characterization and labeling. However, derivatization chemistries used in most conventional iodination procedures may cause substantial alterations in protein structure and function. The IPy2BF4 reagent [bis(pyridine)iodonium (I) tetrafluoroborate] has been shown to be an effective iodinating reagent for peptides. Herein we report the first application of IPy2BF4 in protein iodination in an aqueous medium using three representative substrates:  insulin, lysozyme, and the enzyme 1,3-1,4-β-d-4-glucanohydrolase. Our results show that IPy2BF4 has clear advantages over existing methods in that the reaction is quantitative, fast, and selective for the most accessible Tyr residues of a protein, and it preserves the functional integrity of the protein when moderate Tyr labeling levels are pursued.