Oxidatively induced DNA damage is implicated in disease, unless it is repaired by DNA repair. DNA repair proteins may be used as early detection and therapeutic biomarkers in cancer and other diseases. For this purpose, the measurement of the expression level of these proteins in vivo will be necessary. We applied LC-MS/MS with isotope-dilution for the measurement of human 8- hydroxyguanine-DNA glycosylase and E. coli formamidopyrimidine DNA glycosylase. We purified 15N- labeled analogs of these proteins and used them as internal standards. Proteins were digested with trypsin and analyzed by LC-MS/MS. Numerous tryptic peptides were identified. Statistically significant protein scores were obtained. Product ion spectra of tryptic peptides were recorded and defined. Mixtures of the proteins and their 15N-labeled analogs were analyzed by selected-reaction monitoring. The results suggest that the methodology developed would be suitable for the measurement of DNA repair proteins in vivo as potential biomarkers for cancer and other diseases.
Citation: ACS Journal of Proteome Research
Pub Type: Journals
DNA repair, DNA repair proteins, human OGG1, LC-MS/MS, stable isotope-labeling, labeled internal standards