Recognition of left-handed Z-DNA of short unmodified oligonucleotides under physiological ionic strength conditions.

The left-handed Z-DNA form of the short unmodified alternating guanine-cytosine oligonucleotides, 5'-(dGdC)(24) and 5'-(dGdC)(18), was selectively detected under physiological ionic strength and pH conditions using the anionic nickel(II) porphyrin, NiTPPS. No spectroscopic signal was observed for NiTPPS with any right-handed oligonucleotides under identical conditions. The 48mer 5'-(dGdC)(24) Z-form was detected at concentrations as low as 100nM.