Bolton-Hunter reagent is the N-hydroxysuccinimide ester of iodinated p-hydroxyphenylpropionic acid. Bolton-Hunter method labels terminal amino groups with a radioiodinated phenolic residue, effectively introducing radioactive iodine into proteins and peptides. Since it is a non-oxidative technique, it is “less harsh” to proteins than alternative methods in turn retaining a high degree of binding activity to receptors.
The mono-iodinated form is generally recommended for most Bolton-Hunter iodinations. The di-iodinated form is the same as the mono-iodinated with the difference of doubling the specific activity (4400 Ci/mmol) for each molecule of reagent. This is used when the extra sensitivity is important relative to decrease in stability.