Premium
Photodynamic induction of DNA–protein cross‐linking in solution by several sensitizers and visible light
Author(s) -
Villanueva A.,
Cañete M.,
Trigueros C.,
RodriguezBorlado L.,
Juarranz A.
Publication year - 1993
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360330206
Subject(s) - chemistry , singlet oxygen , methylene blue , dna , photosensitizer , photodegradation , dna damage , tryptophan , histone , photochemistry , stereochemistry , oxygen , biochemistry , organic chemistry , photocatalysis , amino acid , catalysis
The combined effect of several sensitizers and light on H 2 O or D 2 O solutions of DNA‐histone complexes, as well as the significance of singlet oxygen ( 1 O 2 ), in this photosensitizing reaction has been studied. On H 2 O solutions, the production of 1 O 2 , as well as the formation of DNA‐protein cross‐links (DPCs), were found to be dependent on light dose for all the sensitizers. Mesotetra (4N‐methylpyridyl) porphine (T 4 MPyP), methylene blue (MB), and toluidine blue (TB) were the best photosensitizers with regard to tryptophan photolysis, followed by hematoporphyrin (HP), thioflavine T (TT), and pyronin G (PG). The formation of DPCs showed high initial rates, reaching a plateau at dose over 90 J/cm 2 . Under these irradiation conditions, the percentage of DPCs induced by the sensitizers decreases in the order T 4 MPyP > MB > TB ≫ HP ≈ TT ≫ PG (≈0). These DPCs were totally destroyed with proteinase K (15μg/ml). The irradiation of the DNA‐histone‐sensitizer solutions in the presence of L ‐carnosine (5 × 10 ‐4 M ) produced approximately a 50% of DPCs inhibition for T 4 MPyP, MB, and TB, and a total inhibition for HP, TT, and PG. The substitution of H 2 O by D 2 O as solvent significantly increased the photodegradation of tryptophan, as well as the photoinduction of DPCs by the sensitizers. The results obtained indicate that singlet oxygen is the main agent responsible in the DNA–protein cross‐linking formation. © 1993 John Wiley & Sons, Inc.