Application of HPLC in the 32P-postlabeling assay

The postlabeling procedure for the detection of DNA modifications entails enzyme-catalyzed incorporation of 32P into nucleotides and chromatographic separation of radiolabeled products for quantification. Alternate versions of this procedure have been developed which vary in sensitivity and in applicability for the detection of different DNA adducts. Methods that utilize HPLC in either of two steps in the procedure (i.e., the separation of modified and unmodified nucleotides before the labeling reaction or the resolution of 32P-labeled adducts) are applicable for the detection of alkyl adducts as well as bulky, hydrophobic adducts and are discussed in this review. In some cases, postlabeling assays have been tailored for the quantitative detection of specific adducts. Use of multiple optimized postlabeling methods to analyze one DNA sample may enable identification of multiple specific adducts in human DNA. The widest and most promising applications for adduct detection with the postlabeling assay are for previously characterized adducts, where adduct standards are available for optimization and characterization of recovery in the assay. 32P-Postlabeling is a powerful way to measure DNA adducts as it is very sensitive. However, caution should be applied in drawing conclusions from postlabeling studies without appropriate corroborative data using another adduct detection method or without appropriate method development preceding the study. Examples of applications in human, laboratory animal, and environmental studies are available.