Syntheses and DNA binding of new cationic porphyrin-tetrapeptide conjugates

Gábor Mezo, Levente Herényi, Jan Habdas, Zsuzsa Majer, Beata Myśliwa-Kurdziel, Katalin Tóth, Gabriella Csík

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Recently cationic porphyrin-peptide conjugates were synthesized to enhance the cellular uptake of porphyrins or deliver the peptide moiety to the close vicinity of nucleic acids. DNA binding of such compounds was not systematically studied yet. We synthesized two new porphyrin-tetrapeptide conjugates which can be considered as a typical monomer unit corresponding to the branches of porphyrin-polymeric branched chain polypeptide conjugates. Tetra-peptides were linked to the tri-cationic meso-tri(4-N-methylpyridyl)-mono-(4-carboxyphenyl) porphyrin and bi-cationic meso-5,10-bis(4-N-methylpyridyl)-15,20-di-(4- carboxyphenyl)porphyrin. DNA binding of porphyrin derivatives, and their peptide conjugates was investigated with comprehensive spectroscopic methods. Titration of porphyrin conjugates with DNA showed changes in Soret bands with bathocromic shifts and hypochromicities. Decomposition of absorption spectra suggested the formation of two populations of bound porphyrins. Evidence provided by the decomposition of absorption spectra, fluorescence decay components, fluorescence energy transfer and induced CD signals reveals that peptide conjugates of di- and tricationic porphyrins bind to DNA by two distinct binding modes which can be identified as intercalation and external binding. Tri-cationic structure and elimination of negative charges in the peptide conjugates are preferable for the binding. Our findings provide essential information for the design of DNA-targeted porphyrin-peptide conjugates.

Original languageEnglish
Pages (from-to)36-44
Number of pages9
JournalBiophysical Chemistry
Volume155
Issue number1
DOIs
Publication statusPublished - Apr 1 2011

Keywords

  • Cationic porphyrin
  • DNA-porphyrin binding
  • Induced CD-signal
  • Intercalation
  • Photophysical parameters
  • Porphyrin-peptide conjugate

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Organic Chemistry

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