Interactions of new water-soluble porphyrins with nucleic acids.
Item
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Title
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Interactions of new water-soluble porphyrins with nucleic acids.
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Identifier
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AAI9020821
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identifier
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9020821
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Creator
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Xu, Zhengjiu.
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Contributor
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David K. Lavallee
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Date
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1990
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, General | Chemistry, Inorganic | Chemistry, Biochemistry
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Abstract
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Tetrakis(p-aminomethylphenyl)porphyrin (TAMPP) and its N-methyl derivative N-MTAMPP were synthesized because (1) The peripheral amino groups of both porphyrins are predicted to be protonated at neutral pH, which is an important property for studies of interactions of porphyrins with double stranded nucleic acid, and (2) N-methylated porphyrins may be used for selective alkylation of DNA studies. It was found that the {dollar}meso{dollar}-aryl substituents of N-MTAMPP rotate slower than the NMR time scale, which cause stronger basicity of the amino groups of N-MTAMPP than those of TAMPP.;Four methods have been used to study the binding of TAMPP and N-MTAMPP with nucleic acid: (1) Induced circular dichroism (CD) spectra of porphyrin-nucleic acid systems indicate directly that the two porphyrins do interact and bind to nucleic acids; (2) Fluorescence spectra disclose that there are different binding modes between porphyrins and nucleic acids. Intercalation into and electrostatic attraction with nucleic acids result in hypochromic character. Insertion into groove of nucleic acid results in hyperchromic character; (3) The hypochromic and bathochromic characteristics of visible spectra of porphyrins on binding to nucleic acids is used to deduct modes of binding; (4) A new method of competitive-binding data treatment makes it straight forward to determine the binding constant of a porphyrin with nucleic acids.;The information uncovered by above methods are consistent. It was found that: (1) Both TAMPP and N-MTAMPP bind mostly at A-T rich regions of DNA; (2) Both TAMPP and N-MTAMPP bind on the outside of DNA. The TAMPP may bridge two strands of DNA at the narrow groove, interacting by electrostatic attraction with two adjacent negatively charged phosphate groups. In contrast, N-MTAMPP may insert into alternate major grooves of DNA and cause the two adjacent grooves to be deformed; (3) Both TAMPP and N-MTAMPP can intercalate into Poly(dG-dC){dollar}\bullet{dollar}Poly(dG-dC); (4) All of the porphyrin-nucleic acid systems have relative high affinity constant s ({dollar}\geq{dollar}10{dollar}\sp6{dollar}).;Metalloporphyrins, Mn(III){dollar}\bullet{dollar}TAMPP and Co(II){dollar}\bullet{dollar}N-MTAMPP, were synthesized. They have the higher binding affinities (10{dollar}\sp7{dollar}) to DNA than the metal free forms.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
