Optimization of Iodination of [125I]-N-Succinimidyl-Para-Iodobenzoate Using Chloramine-T for Labeling of Proteins

Generally, indirect radioiodination of proteins using N-succinimidyl-iodobenzoates preserve the biological function of the protein due the mild labeling conditions. However, a drawback is that the two-step procedure often gives a low overall labeling yield. For this reason the production of ¹²⁵I] N-succinimidyl-para-iodobenzoate (¹²⁵I]SPIB), using Chloramine-T as an oxidant, was optimized regarding substrate, oxidant, reaction time, and volume of the reaction mixture and found to be 86±6%. Produced ¹²⁵I]SPIB was successfully used for the labeling of monoclonal antibodies.