A Fluorophore‐labeled Peptide of Human Ribosomal Protein S3 for the Detection of the 8‐Oxoguanine within the Cells

Detection and quantification of 8-oxo-7,8-dihydroguanine (8-oxoG) within cells are important for the study of the molecular mechanisms in cancer. Human ribosomal protein S3 (hRpS3), which involved in DNA repair, has high binding affinity to 8-oxoG. We developed an imaging probe to detect 8-oxoG using a specific peptide of hRpS3. Sequence analysis was conducted to elucidate the 8-oxoG-specific binding region of hRpS3, and three truncated mutants, D1 (amino acids 1–85), D2 (amino acids 86–159), and D3 (amino acids 160–242), were constructed. Both wild-type-hRpS3 and D2 were able to bind 8-oxoG, which is consistent with the results of a previous report on the role of K134 in Drosophila melanogaster RpS3. We synthesized a specific peptide and covalently linked with a fluorophore (FPR-552, similar to Cy3) to generate an 8-oxoG imaging probe. Our 8-oxoG S3-probe successfully detected the presence of 8-oxoG in damaged cells. Furthermore, this probe has threefold higher sensitivity than 8-oxoG DNA lesion antibody.