Binding, Electrochemical Activation, and Cleavage of DNA by Cobalt(II)
Tetrakis-<i>N</i>-methylpyridyl Porphyrin and Its β-Pyrrole Brominated Derivative
Shivaraj Yellappa
Jaldappagari Seetharamappa
Lisa M. Rogers
Raghu Chitta
Ram P. Singhal
Francis D'Souza
10.1021/bc060153x.s001
https://acs.figshare.com/articles/journal_contribution/Binding_Electrochemical_Activation_and_Cleavage_of_DNA_by_Cobalt_II_Tetrakis_i_N_i_methylpyridyl_Porphyrin_and_Its_Pyrrole_Brominated_Derivative/3047482
The binding of nucleic acids by water-soluble cobalt(II) tetrakis-<i>N</i>-methylpyridyl porphyrin, (TMPyP)Co, and its
highly electron-deficient derivative cobalt(II) tetrakis-<i>N</i>-methyl pyridyl-β-octabromoporphyrin, (Br<sub>8</sub>TMPyP)Co,
was investigated by UV−visible absorption, circular dichroism (CD), and electrochemical and gel electrophoresis
methods. The changes of the absorption spectra during the titration of these complexes with polynucleotides
revealed a shift in the absorption maxima and a hypochromicity of the porphyrin Soret bands. The intrinsic binding
constants were found to be in the range of 10<sup>5</sup>−10<sup>6</sup> M<sup>-1</sup>. These values were higher for the more electron-deficient
(Br<sub>8</sub>TMPyP)Co. Induced CD bands were noticed in the Soret region of the complexes due to the interaction of
these complexes with different polynucleotides, and an analysis of the CD spectra supported a mainly external
mode of binding. Electrochemical studies revealed the cleavage of polynucleotides by (TMPyP)Co and
(Br<sub>8</sub>TMPyP)Co in the presence of oxygen preferentially at the A−T base pair region. Gel electrophoresis
experiments further supported the cleavage of nucleic acids. The results indicate that the β-pyrrole brominated
porphyrin, (Br<sub>8</sub>TMPyP)Co, binds strongly and cleaves nucleic acids efficiently as compared with (TMPyP)Co.
This electrolytic procedure offers a unique tool in biotechnology for cleaving double-stranded DNA with specificity
at the A−T regions.
2006-11-15 00:00:00
porphyrin Soret bands
cobalt
Br 8TMPyP Induced CD bands
absorption
gel electrophoresis methods
Electrochemical
cleavage
acid
region
UV
Br 8TMPyP
gel electrophoresis experiments
DNA
binding
complex
spectra
polynucleotide