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PHOTOCHEMISTRY OF QUINOLYLMETHYLISOTHIORONIUM SALTS. GUANINE SELECTIVE DNA PHOTOCLEAVAGE REAGENTS
Author(s) -
HENRIKSEN U.,
LARSEN C.,
KARUP G.,
JEPPESEN C.,
NIELSEN P. E.,
BUCHARDT O.
Publication year - 1991
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.1751-1097.1991.tb03632.x
Subject(s) - chemistry , guanine , reagent , dna , photochemistry , combinatorial chemistry , nucleotide , biochemistry , organic chemistry , gene
— Quinolylmethylisothioronium salts ( 1a and 4a ) cleave DNA upon irradiation. The cleavage is more than 10‐fold enhanced by piperidine treatment and subsequently shows a high preference for guanines. Photolysis of 1a , 2a and 4a in water at Λ > 300 nm resulted in photoheterolysis. Irradiation of 1a in 2‐propanol gave only products from photohomolysis, whereas irradiation of 1a in methanol and 2a and 4a in 2‐propanol resulted in products from both photoheterolysis and photohomolysis. Quantum yields for the disappearance of 1a in water and 2‐propanol were determined. The presence or absence of oxygen had no effect in water, whereas oxidation products were observed upon irradiation in methanol and 2‐propanol in the presence of oxygen. The guanine specific DNA photoreaction is proposed to take place by alkylation at N7 via the quinolylmethyl carbocation and thus to represent a photoalkylation.