Pyridyl derivatives provide new pathways for labeling protein with fac-[188Re(CO)3(H2O)3]+

The purpose of this work was to indirect label IgG with fac-[188Re(CO)3(H2O)3]+ and to check the radiochemical behavior of the labeled product. The compound of (bis(2-pyridylmethyl)-amino)-acetic acid (L2H) was synthesized and labeled with fac-[188Re(CO)3(H2O)3]+. The labeling yield of 188Re(CO)3–L2H was more than 90%. The effects of protein concentration, reaction time, pH and reaction temperature of labeling of IgG with 188Re(CO)3–L2H were investigated. The conjugation conditions were optimized. The labeled product was analyzed by size exclusion HPLC and TLC. The stability of 188Re(CO)3–L2H–IgG in vitro was high. The results of this study may be useful for [188Re(CO)3(H2O)3]+ labeling of protein for radioimmunotherapy.