RADIOHALOGENATION OF PROTEINS - AN OVERVIEW OF RADIONUCLIDES, LABELING METHODS, AND REAGENTS FOR CONJUGATE LABELING

Methods of radiolabeling proteins have been of interest for a variety of applications for several decades. Although many different radionuclides have been used to radiolabel proteins (1-7), the largest number of labeled-protein studies have used radionuclides of iodine, principally iodine-125 and iodine-131. These radionuclides of iodine have properties which are adequate for a number of different applications, and the radionuclides are relatively easy to use and readily available at a nominal cost from commercial sources. Other radionuclides of the halogen group, while not studied extensively to date, could potentially be utilized in protein labeling. In fact, there are a number of radiohalogen nuclides, with a wide range of half-lives and radiochemical properties, which could be used for a variety of different purposes. As a group, radiohalogens may be particularly useful for radiolabeling of proteins because (a) their chemistry is well-understood (perhaps with the exception of astatine), (b) they form stable covalent bonds, (c) their steric and electronic nature can be expected to cause minimal alteration to the protein, (d) high specific activity radiolabeling can be accomplished, and (e) radionuclides with many different half-lives and photon or particle emissions are obtainable. © 1992, American Chemical Society. All rights reserved.