Thioguanine is a purine analogue used in cancer chemotherapy. It is the 6-thione analogue of the endogenous 6-OH purine base guanine. In the cell thioguanine is converted to the ribonucleotides: 6-thioguanosine-5'-phosphate and 6-thioinosine-5'-phosphate. These fraudulent nucleotides produce their cytoto, Xenopus/Amphibian,ic effects by several mechanisms, e.g. inhibitory action on de novo purine synthesis, and may themselves be incorporated into DNA. Thioguanine has a molecular weight of 167 Da. This antibody is specific for thioguanine. Cross-reactivity is seen with 6-(methylthio)purine, but not with various other thioguanine analogs.