Use of oligonucleotides containing ethenoadenine to study the repair of this DNA lesion. Determination of individual and collective repair activities.

Oligonucleotide duplexes of a defined sequence containing one 1,N6-ethenoadenosine (EA) were synthesized and used as substrates to study the repair of this DNA lesion in cell homogenates of peripheral mononuclear blood cells of 39 male and female workers, exposed to vinyl chloride. These data were compared to data from 39 employees of the same company working in other production plants and to data from a control group of 39 persons, living in an area without vinyl chloride production. After incubation of the 5'- and 3'-labeled oligonucleotide duplex with cell homogenate, a specific nicking activity, releasing the deoxyribosyl phosphate originally carrying the EA, was found. This activity was used to determine the individual and collective repair activities for ethenoadenine. The exposed group showed a mean of 158.5 +/- 39.9 (SD) fmol product fragment and did not differ significantly from the mean value of the two control groups with 156.5 +/- 42.9 fmol and 161.2 +/- 53.6 fmol, respectively. Large interindividual variations were found, ranging from 4.9-fold in the exposed to 8.2- and 7.2-fold in the control groups. The development of an assay for ethenoadenine repair is significant for understanding the role of EA repair in eukaryotic cells.