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Evaluation of binding selectivities and affinities of platinum‐based quadruplex interactive complexes by electrospray ionization mass spectrometry
Author(s) -
Pierce Sarah E.,
Kieltyka Roxanne,
Sleiman Hanadi F.,
Brodbelt Jennifer S.
Publication year - 2009
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21130
Subject(s) - chemistry , circular dichroism , electrospray ionization , platinum , ruthenium , g quadruplex , affinities , stereochemistry , metal , crystallography , mass spectrometry , organic chemistry , catalysis , dna , biochemistry , chromatography
The quadruplex binding affinities and selectivities of two large π‐surface Pt II phenanthroimidazole complexes, as well as a smaller π‐surface platinum bipyridine complex and a larger Ru II complex, were evaluated by electrospray ionization mass spectrometry. Circular dichroism (CD) spectroscopy was used to determine the structures of various quadruplexes and to study the thermal denaturation of the quadruplexes in the absence and presence of the metal complexes. In addition, chemical probe reactions with glyoxal were used to monitor the changes in the quadruplex conformation because of association with the complexes. The platinum phenanthroimidazole complexes show increased affinity for several of the quadruplexes with elongated loops between guanine repeats. Quadruplexes with shorter loops exhibited insubstantial binding to the transition metal complexes. Similarly binding to duplex and single strand oligonucleotides was low overall. Although the ruthenium‐based metal complex showed somewhat enhanced quadruplex binding, the Pt II complexes had higher quadruplex affinities and selectivities that are attributed to their square planar geometries. The chemical probe reactions using glyoxal indicated increased reactivity when the platinum phenanthroimidazole complexes were bound to the quadruplexes, thus suggesting a conformational change that alters guanine accessibility. © 2008 Wiley Periodicals, Inc. Biopolymers 91: 233–243, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com