Binding, Electrochemical Activation, and Cleavage of DNA by Cobalt(II) Tetrakis-N-methylpyridyl Porphyrin and Its mg src="http://pubs.acs.org/images/gifchars/beta2.gif" border="0" align="midd

详细信息    查看全文

• 作者：Shivaraj Yellappa ; Jaldappagari Seetharamappa ; Lisa M. Rogers ; Raghu Chitta ; Ram P. Singhal ; Francis D'Souza
• 刊名：Bioconjugate Chemistry
• 出版年：2006
• 出版时间：November 2006
• 年：2006
• 卷：17
• 期：6
• 页码：1418 - 1425
• 全文大小：295K
• 年卷期：v.17,no.6(November 2006)
• ISSN：1520-4812

文摘

The binding of nucleic acids by water-soluble cobalt(II) tetrakis-N-methylpyridyl porphyrin, (TMPyP)Co, and itshighly electron-deficient derivative cobalt(II) tetrakis-N-methyl pyridyl-mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-octabromoporphyrin, (Br₈TMPyP)Co,was investigated by UV-visible absorption, circular dichroism (CD), and electrochemical and gel electrophoresismethods. The changes of the absorption spectra during the titration of these complexes with polynucleotidesrevealed a shift in the absorption maxima and a hypochromicity of the porphyrin Soret bands. The intrinsic bindingconstants were found to be in the range of 10⁵-10⁶ M^-1. These values were higher for the more electron-deficient(Br₈TMPyP)Co. Induced CD bands were noticed in the Soret region of the complexes due to the interaction ofthese complexes with different polynucleotides, and an analysis of the CD spectra supported a mainly externalmode of binding. Electrochemical studies revealed the cleavage of polynucleotides by (TMPyP)Co and(Br₈TMPyP)Co in the presence of oxygen preferentially at the A-T base pair region. Gel electrophoresisexperiments further supported the cleavage of nucleic acids. The results indicate that the mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-pyrrole brominatedporphyrin, (Br₈TMPyP)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 specificityat the A-T regions.