SYNTHESIS OF I-125 LABELED OLIGONUCLEOTIDES FROM TRIBUTYLSTANNYLBENZAMIDE CONJUGATES

A rapid and efficient method for the synthesis of I-125-labeled oligod eoxynucleotides ([I-125]ODNs) is described. The key intermediates are tributylstannylbenzamide-modified ODNs (Sn-ODNs). Reaction conditions are described for the preparation of 5'-modified Sn-ODNs. Treatment wi th NaI and chloramine T gave conversion to the desired I-ODN, which wa s easily isolated by reversed phase chromatography. Thermal denaturati on (T-m) studies showed that hybridization properties were not disturb ed by the 4-iodobenzamide modification. An [I-125]ODN was prepared and characterized by hybridization to P-32-labeled DNA targets. Sequence specific cleavage of the target DNA strand by I-125 was measured.