Robert Buscaglia

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Isothermal titration calorimetry, ITC, has been used to determine the thermodynamics (DeltaG, DeltaH, and -TDeltaS) for binding netropsin to a number of DNA constructs. The DNA constructs included: six different 20-22mer hairpin forming sequences and an 8-mer DNA forming a duplex dimer. All DNA constructs had a single -AT-rich netropsin binding with one of(More)
Regulation of the structural equilibrium of G-quadruplex-forming sequences located in the promoter regions of oncogenes by the binding of small molecules has shown potential as a new avenue for cancer chemotherapy. In this study, microcalorimetry (isothermal titration calorimetry and differential scanning calorimetry), electronic spectroscopy(More)
G-quadruplexes (GQ) are formed by the association of guanine-rich stretches of DNA. Certain small molecules can influence kinetics and thermodynamics of this association. Understanding the mechanism of ligand-assisted GQ folding is necessary for the design of more efficient cancer therapeutics. The oligonucleotide d(TAGGG)(2) forms parallel bimolecular GQ(More)
Polyethylene glycols (PEGs) are widely used to perturb the conformations of nucleic acids, including G-quadruplexes. The mechanism by which PEG alters G-quadruplex conformation is poorly understood. We describe here studies designed to determine how PEG and other co-solutes affect the conformation of the human telomeric quadruplex. Osmotic stress studies(More)
We completed a biophysical characterization of the c-MYC proto-oncogene P1 promoter quadruplex and its interaction with a cationic porphyrin, 5,10,15,20-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP4), using differential scanning calorimetry, isothermal titration calorimetry, and circular dichroism spectroscopy. We examined three different 24-mer(More)
Thermal denaturation profiles of several model oligonucleotides of the human telomere DNA sequence including d[A(GGGTTA)(3)GGG] (Tel22) were determined using circular dichroism (CD), fluorescence of adenine → 2-aminopurine analogs, and fluorescence resonance energy transfer (FRET) to monitor the unfolding process at specific locations within the quadruplex.(More)
The factors that determine the conformation and stability of G-quadruplex forming sequences remain poorly understood. Here we demonstrate the influence of cosolvents on the conformation and stability of the human telomeric sequence d(A(GGGTTA)3GGG)) in both K(+) and Na(+) containing solutions using a combination of circular dichroism, NMR, and(More)
Mutations occur at four specific sites in the hTERT promoter in >75% of glioblastomas and melanomas, but the mechanism by which the mutations affect gene expression remains unexplained. We report biophysical computational studies that show that the hTERT promoter sequence forms a novel G-quadruplex structure consisting of three contiguous, stacked parallel(More)
G-quadruplexes, DNA tertiary structures highly localized to functionally important sites within the human genome, have emerged as important new drug targets. The putative G-quadruplex-forming sequence (Pu27) in the NHE-III(1) promoter region of the c-Myc gene is of particular interest as stabilization of this G-quadruplex with TMPyP4 has been shown to(More)
Fluorescent reporter groups have served for many years as sensitive probes of macromolecular structure. Such probes can be especially useful in comparative studies such as detection of conformational changes and discrimination among structural models. Spectroscopic methods such as fluorescence are attractive because they are rapid, require small amounts of(More)