13] Radioiodination by use of the Bolton-Hunter and related reagents

Abstract

This chapter discusses the radioiodination by the use of the Bolton-Hunter and related reagents. Iodinated N-succinimidyl 3-(4-hydroxyphenyl)propionate (Bolton-Hunter reagent) is the first conjugation reagent that has been widely used to prepare tracers for immunoassay. Similar reagents derived from methyl p-hydroxybenzimidate and diazotized aniline have been synthesized and used to iodinate proteins, but not specifically for use in immunoassay. The Bolton-Hunter reagent is a 125I-labeled acylating agent prepared by the chloramine-T method that reacts spontaneously and under mild conditions primarily with lysine residues. Use of this reagent supplements, the chloramine-T and lactoperoxidase methods, in which radioactive iodide is introduced into the phenol ring of tyrosine or related moieties and to some extent into histidine residues. The Bolton-Hunter reagent is an excellent alternative in case labeling tyrosine that leads to loss of immunoactivity or biological activity, or when the substrate lacks the appropriate group. Since the Bolton-Hunter reagent was introduced, it has been used to label a wide variety of targets, including viruses and cell lysates as well as pure compounds. One of its most important applications has been the preparation of iodinated antigens and hapten derivatives of high specific activity for use in radioimmunoassay.