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Quenching of the fluorescence of aromatic pterins by deoxynucleotides.

Authors
  • Petroselli, Gabriela
  • Dántola, M Laura
  • Cabrerizo, Franco M
  • Lorente, Carolina
  • Braun, André M
  • Oliveros, Esther
  • Thomas, Andrés H
Type
Published Article
Journal
The Journal of Physical Chemistry A
Publisher
American Chemical Society
Publication Date
Mar 05, 2009
Volume
113
Issue
9
Pages
1794–1799
Identifiers
DOI: 10.1021/jp8101496
PMID: 19199487
Source
Medline
License
Unknown

Abstract

Steady-state and time-resolved studies of the fluorescence of four aromatic unconjugated pterins (pterin (Ptr), 6-(hydroxymethyl)pterin (Hmp), 6-methylpterin (Mep), and 6,7-dimethylpterin (Dmp)) in aqueous solutions in the presence of different nucleotides (2'-deoxyguanosine 5'-monophosphate (dGMP), 2'-deoxyadenosine 5'-monophosphate (dAMP), and 2'-deoxycytosine 5'-monophosphate (dCMP)) have been performed using the single-photon counting technique. The singlet excited states of acid forms of pterins are deactivated by purine nucleotides (dGMP and dAMP) via a combination of dynamic and static processes. The efficiency of the dynamic quenching is high, independently of the nature of the purine base of the nucleotide and of the chemical structure of the substituents linked to the pterin moiety. Analysis of the static quenching indicates that ground-state association between pterins and purine nucleotides takes place, but the formation of the corresponding complexes is significant only at relatively high reactant concentrations. The quenching of the fluorescence of acid forms of pterin derivatives by dCMP, a pyrimidine nucleotide, is slightly less efficient than the quenching by purine nucleotides and is purely dynamic. In alkaline media, the fluorescence quenching is much less efficient than in acidic media, the deactivation by purine nucleotides being purely dynamic, whereas quenching by dCMP is negligible. Possible mechanisms for the quenching of fluorescence of pterin derivatives by the different nucleotides are discussed.

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