SEQUENCE-SPECIFIC MODIFICATION OF GUANOSINE IN DNA BY A C-60-LINKED DEOXYOLIGONUCLEOTIDE - EVIDENCE FOR A NON-SINGLET OXYGEN MECHANISM

A C-60-linked deoxyoligonucleotide (C-60-DON-1) was prepared from brom oacetate 3. This C-60-oligonucleotide conjugate was hybridized to a co mplementary single-stranded DNA. This system reacted with light and ox ygen to damage only guanosines in the single-stranded region which are closest to C-60. The damage did not involve O-1(2) as the active spec ies but rather resulted from a single electron-transfer mechanism betw een guanosine and C-3(60), as shown by comparison experiments with eos in-attached DON-1 and by the use of singlet oxygen quenchers. (C) 1996 Elsevier Science Ltd