Thioguanylate

Thioguanylate refers to guanylate nucleotides in which the purine base guanine is modified by substitution of an oxygen atom with sulfur, yielding thio-guanine analogs. The substitution most commonly occurs at the 6-position of the guanine ring, producing 6-thioguanine-containing nucleotides. The term encompasses thioguanosine monophosphate and related diphosphate and triphosphate derivatives used in biochemical research as nucleotide analogs.

In chemistry and biology, thioguanylate derivatives are typically synthetic tools used to study nucleotide recognition by enzymes such as DNA and RNA polymerases, as well as DNA repair and transcription processes. The sulfur substitution alters hydrogen-bonding properties and enzyme interactions relative to native guanine, which can affect base pairing, incorporation by polymerases, and metabolic processing.

In medicine, one well-known example related to this class is 6-thioguanine, a purine analog with immunosuppressive and anticancer activity that is used clinically in some regimens. Its nucleoside and nucleotide forms have been explored for therapeutic potential, though clinical use is tempered by toxicity and dose-limiting side effects. Research on thioguanylate derivatives continues to investigate their usefulness as selective probes of nucleotide metabolism, as substrates or inhibitors in enzymatic assays, and as possible leads for therapeutic development.