DNA MODIFICATION PROMOTED BY WATER-SOLUBLE NICKEL(II) SALEN COMPLEXES- A SWITCH TO DNA ALKYLATION

Reaction of a 17-base hairpin-forming oligonucleotide with (4-trimethy laminophenyl)ethylenediimino]nickel(II) perchlorate, 2, and KHSO5 prod uced two types of high molecular weight products, an alkaline-labile s pecies and a nonalkaline-labile species, which co-migrated on gel elec trophoresis. Upon treatment with piperidine, the base-labile derivativ e led to strand scission products only at accessible guanine residues that were not part of a Watson-Crick duplex. The formation of higher m olecular weight species is proposed to occur via a highly reactive lig and-centered radical acting as a DNA alkylating agent.