Chemistry

Tying Up Triplexes

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Science  16 Feb 2001:
Vol. 291, Issue 5507, pp. 1161
DOI: 10.1126/science.291.5507.1161a

The nucleotide bases of single stranded DNA can form hydrogen bonds with exposed portions of the paired bases of duplex DNA; the binding of this single strand in the major groove then creates a triple-stranded DNA. Triplex formation depends in a complex way on sequence, although repeated purine (Pu) and pyrimidine (Py) tracts tend to favor formation. Ihara et al. report that Cu2+ ions can be used to join purine tracts by means of a conjugated glutamic acid. This hybrid single strand, containing an inverted repeat, can then form a triple-stranded adduct with palindromic duplex sequences. The Cu2+ ion appears to act as an allosteric effector that helps stabilize the triplex cooperatively. Such approaches could prove useful in synthesizing sensors for target repetitive DNA sequences that occur in some genetic diseases and at telomeres. — PDS

J. Am. Chem. Soc., in press.

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