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Sequence-Selective Binding of Phenazinium Dyes Phenosafranin and Safranin O to Guanine-Cytosine Deoxyribopolynucleotides: Spectroscopic and Thermodynamic Studies

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Title Sequence-Selective Binding of Phenazinium Dyes Phenosafranin and Safranin O to
Guanine-Cytosine Deoxyribopolynucleotides: Spectroscopic and Thermodynamic Studies
 
Creator Saha, Ishita
Hossain, Maidul
Kumar, G Suresh
 
Subject Drug Development/Diagnostics & Biotechnology
 
Description The sequence selectivity of the DNA binding of the phenazinium dyes phenosafranin and safranin O have
been investigated with four sequence-specific deoxyribopolynucleotides from spectroscopic and calorimetric
studies. The alternating guanine-cytosine sequence selectivity of the dyes has been revealed from binding
affinity values, circular dichroism, thermal melting, competition dialysis, and calorimetric results. The binding
affinities of both the dyes to the polynucleotides were of the order of 105 M-1, but the values were higher for
the guanine-cytosine polynucleotides over adenine-thymine ones. Phenosafranin had a higher binding affinity
compared to safranin O. Isothermal titration calorimetric studies revealed that the binding reactions were
exothermic and favored by negative enthalpy and predominantly large positive entropy contributions in all
cases except poly(dA) ยท poly(dT) where the profile was anomalous. Although charged, nonpolyelectrolytic
contribution was revealed to be dominant to the free energy of binding. The negative heat capacity values
obtained from the temperature dependence of enthalpy changes, which were higher for phenosafranin compared
to safranin O, suggested significant hydrophobic contribution to the binding process. In aggregate, the data
presents evidence for the alternating guanine-cytosine base pair selectivity of these phenazinium dyes and
a stronger binding of phenosafranin over safranin O.
 
Publisher American Chemical Society
 
Date 2010
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://www.eprints.iicb.res.in/82/1/JOURNAL_OF_PHYSICAL_CHEMISTRY_B114(46)15278%2D15287;2010[12].pdf
Saha, Ishita and Hossain, Maidul and Kumar, G Suresh (2010) Sequence-Selective Binding of Phenazinium Dyes Phenosafranin and Safranin O to Guanine-Cytosine Deoxyribopolynucleotides: Spectroscopic and Thermodynamic Studies. The Journal of Physical Chemistry B, B114 (46). pp. 15278-15287.
 
Relation http://dx.doi.org/10.1007/s12034-010-0051-7
http://www.eprints.iicb.res.in/82/