Spectroscopic probe for Z-DNA

A derivative of Ru(phen), Ru(DIP)3 (DIP = 4,7-diphenyl 1,10-phenan-throline, Fig. 2) behaves similarly to Ru(phen)i [65,85] with a slightly better enantioselectivity, so that the A Ru(DIP)3 has been used as spectroscopic probe for Z-DNA. This enantioselective property has been applied with photo-reactive complexes, where the Ru(ll) center has been replaced by another metal ion such as Co(III) and Rh(III) (see further). 

A-Ru(DIP),l. Octahedral metal complexes of the 4,7-diphenyl-phenanthroline (DIP) family are versatile probes for Z-form structure. Using both spectroscopic studies of [A-Ru(DIP)3p binding (59, 60) and photochemical cleavage studies with [A-Co(DIP)3] (see below), one observes that the complexes can scan large pieces of primarily B-form DNA and bind exclusively to Z-form sites or sites of other unusual geometries. The battery of spectroscopic techniques described in the first part of this section was used to determine the relative affinity for [Ru(DIP)3] enantiomers to different forms of DNA and to derive spectroscopic probes for Z-like DNA structures. 

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