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THE PHOTOPHYSICAL AND PHOTOCHEMICAL PROCESSES OF TRYPTOPHAN IN INTERACTION WITH POLYNUCLEOTIDES: LASER FLASH PHOTOLYSIS STUDY
Author(s) -
Doan T.,
Toulme J. J.,
Santus R.,
Hélène C.
Publication year - 1981
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1981.tb09002.x
Subject(s) - chemistry , flash photolysis , polynucleotide , tryptophan , photochemistry , quantum yield , triplet state , nucleotide , fluorescence , aqueous solution , photodissociation , stereochemistry , kinetics , molecule , amino acid , organic chemistry , biochemistry , physics , quantum mechanics , reaction rate constant , gene
— The influence of nucleotides or polynucleotides on the photophysics and the photochemistry of tryptophan (Trp) derivatives has been investigated in aqueous solutions using the 265 nm laser flash photolysis technique. In solutions containing mixtures of N ‐acetyltryptophanamide and uridine monophosphate (UMP) or mercurated dUMP, the Trp triplet and the hydrated electron (e aq ) are quenched at almost diffusion controlled rates by the nucleotides leading to uracil reduction. Lysyl‐tryptophyl‐α‐lysine (Lys‐Trp‐Lys) forms stable complexes in solution with normal or mercurated poly(uridylic acid) [poly(U)]. In the Poly(rU)‐Lys‐Trp‐Lys complex the Trp triplet state is completely quenched, whereas the Trp triplet formation quantum yield is enhanced in complexes with mercurated poly(U). In this last case, the ‘heavy atom effect’ is characterized by a shortening of the Trp triplet lifetime in agreement with low temperature experiments. Our results also show that photoionization of Trp does occur in the complexed state with both polymers. The e aq lifetime is however longer with the complexed than with the free peptide.