7-Methylguanine is a modified

purine Purine is a heterocyclic compound, heterocyclic aromatic organic compound that consists of two rings (pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which includ ...

nucleobase Nucleobases, also known as ''nitrogenous bases'' or often simply ''bases'', are nitrogen-containing biological compounds that form nucleosides, which, in turn, are components of nucleotides, with all of these monomers constituting the basic b ...

. It is a methylated version of

guanine Guanine () ( symbol G or Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is called ...

. The 7-methylguanine nucleoside is called

7-methylguanosine 7-Methylguanosine (m7G) is a modified purine nucleoside. It is a methylated version of guanosine and when found in human urine, it may be a biomarker of some types of cancer. In the RNAs, 7-methylguanosine have been used to study and examine the ...

. However, the free 7-methylguanine base is not involved in the synthesis of nucleotides and not incorporated directly into nucleic acids. 7-Methylguanine is a natural inhibitor of

poly (ADP-ribose) polymerase Poly (ADP-ribose) polymerase (PARP) is a family of proteins involved in a number of cellular processes such as DNA repair, genomic stability, and programmed cell death. Members of PARP family The PARP family comprises 17 members (10 putative) ...

(PARP) and tRNA guanine transglycosylase (TGT) - and thus may exert anticancer activity. For example, it was demonstrated that 7-methylguanine could accelerate apoptotic death of BRCA1-deficient breast cancer cells induced by cisplatin and doxorubicin.

References

Nucleobases Purines {{organic-compound-stub