DEOXYADENOSINE AND THYMIDINE BASES HELD PROXIMAL AND DISTAL BY MEANS OF A COVALENTLY-LINKED DIMENSIONAL ANALOG OF DA-CENTER-DOT-DT - INTRAMOLECULAR VS INTERMOLECULAR HYDROGEN-BONDING

Deoxyadenylic acid and deoxythymidilic acid have been attached to a co valently-linked cross section, (sic), on the same side (proximal) and on opposite sides (distal) by synthetic sequences involving various co mbined protection/deprotection steps. The structures in aqueous soluti on buffered at pH 7.0 have been examined by 2D-NOESY NMR spectroscopy. The covalently-linked cross section provides a template that stabiliz es dA . dT base pairing in the proximal isomer at 2 degrees C. In the distal isomer, it contributes to favorable conformations for intermole cular association.