5'-Porphyrin-oligonucleotide conjugates: Synthesis, stability, and spectroscopy

CHED 336

Milan Balaz, milan.balaz@chem.ox.ac.uk1, Jay D. Steinkruger, jsteink2@bigred.unl.edu2, George A. Ellestad, gellestad@verizon.net3, and Nina D. Berova, ndb1@columbia.edu3. (1) Department of Chemistry, University of Oxford, Mansfield Road, OX1 3TA Oxford, United Kingdom, (2) Department of Chemistry, University of Nebraska-Lincoln, Hamilton Hall, Lincoln, NE 68588, (3) Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027
Oligodeoxynucleotides (ODNs) carrying covalently attached porphyrins are of high importance as versatile and powerful molecular probes due to the unique electronic structure of the porphyrin moiety. The porphyrin-DNA studies reported earlier have focused on charged water-soluble porphyrins where electrostatic interactions are the leading forces. The non-charged porphyrins have attracted, so far, much less attention most likely due to their low solubility in aqueous solutions.

To better understand the non-electrostatic interaction of the neutral porphyrin with DNA, and to evaluate the influence of the porphyrin on DNA stability, we have synthesized ODN conjugates with a hydrophilic, non-charged porphyrin attached to the DNA backbone via a natural 5' phosphate linker. Porphyrin-modified ODNs show slightly lower melting temperatures than their unmodified analogs. Absorbance, fluorescence, and circular dichroism studies analyzing both porphyrin-porphyrin and porphyrin-DNA interactions suggest that the porphyrin moiety is not freely rotating but more likely in close contact with the adjacent nucleobases.

 

Undergraduate Research Poster Session: Organic Chemistry
11:00 AM-1:00 PM, Monday, 27 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster

Division of Chemical Education

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006