Abstract
Seven N-terminus modified derivatives of a previously published minor-groove binding polyamide (f-ImPyIm, 1) were synthesized and the biochemical and biophysical chemistry evaluated. These compounds were synthesized with the aim of attaining a higher level of sequence selectivity over f-ImPyIm (1), a previously published strong minor-groove binder. Two compounds possessing a furan or a benzofuran moiety at the N-terminus showed a footprint of 0.5 μM at the cognate ACGCGT site (determined by DNase I footprinting); however, the specificity of these compounds was not improved. In contrast, PyImPyIm (4) produced a footprint of 0.5 μM but showed a superior specificity using the same technique. When evaluated by thermal melting experiments and circular dichroism using ACGCGT and the non-cognate AAATTT sequence, all compounds were shown to bind in the minor-groove of DNA and stabilize the cognate sequence much better than the non-cognate (except for the non-amido-compound that did not bind either sequence, as expected). PyImPyIm (4) was interesting as the ΔTm for this compound was only 4 °C but the footprint was very selective. No binding was observed for this compound with a third DNA (non-cognate, ACCGGT). ITC studies on compound 4 showed exothermic binding with ACGCGT and no heat change was observed for titrating the compound to the other two DNA sequences. The heat capacity (ΔCp) of the PIPI/ACGCGT complex calculated from the hydrophobic interactions and SASA calculations was comparable to the experimental value obtained from ITC (-146 cal mol-1 K-1). SPR results provided confirmation of the sequence specificity of PyImPyIm (4), with a Keq value determined to be 7.1 × 106 M-1 for the cognate sequence and no observable binding to AAATTT and ACCGGT. Molecular dynamic simulations affirmed that PyImPyIm (4) binds as a dimer in an overlapped conformation, and it fits snugly in the minor-groove of the ACGCGT oligonucleotide. PyImPyIm (4) is an especially interesting molecule, because although the binding affinity is slightly reduced, the specificity with respect to f-ImPyIm (1) is significantly improved.
Original language | English (US) |
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Pages (from-to) | 5266-5276 |
Number of pages | 11 |
Journal | Bioorganic and Medicinal Chemistry |
Volume | 16 |
Issue number | 9 |
DOIs | |
State | Published - May 1 2008 |
Externally published | Yes |
Keywords
- Binding
- DNA
- Minor-groove
- N-terminus
- Polyamide
ASJC Scopus subject areas
- Biochemistry
- Molecular Medicine
- Molecular Biology
- Pharmaceutical Science
- Drug Discovery
- Clinical Biochemistry
- Organic Chemistry