DETERMINATION OF STYRENE OXIDE ADDUCTS IN DNA AND DNA COMPONENTS

The reaction of styrene oxide with DNA components was studied using se paration by capillary zone electrophoresis (CZE) and detection by nega tive-ion electrospray mass spectrometry (MS). The CZE-MS interface was built for a sector field mass spectrometer. The reaction of styrene o xide with mononucleotides (dGMP, dAMP) was used to optimize the releva nt separation parameters and to gather the first information about the behaviour of the possible products. With these mixtures, sample stack ing procedures were developed and the scope of collision-induced disso ciations were studied. From the fragments recorded, information about the reaction sites in the nucleotides was obtained. Further, the react ion with intact calf thymus DNA was investigated. The DNA was digested into oligonucleotides using the previously described approach with Be nzonase, an unspecific nuclease, and alkaline phosphatase. Styrene oxi de mono-adducts in dinucleotides, trinucleotides and tetranucleotides were detected, whereas pentanucleotides exhibit mono- and discernible amounts of di-adducts. The hexanucleotides were generally modified twi ce. The alkylated species moved faster than the unmodified oligomers.