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Issue 42, 2013
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DNA photoreacts by nucleobase ring cleavage to form labile isocyanates

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Abstract

Differential infrared absorption spectroscopy was used to study the formation of isocyanates and further photo-products in the oligonucleotides dG10, dC10 and dT10 and in their mononucleosides by ultraviolet light at 266 nm. We find that α-cleavage takes place in oligonucleotides and mononucleosides both in films and in solution. The very intense and spectrally isolated isocyanate (N[double bond, length as m-dash]C[double bond, length as m-dash]O) asymmetric stretch vibration at 2277 cm−1 is used as a spectroscopic marker for detection of the photo-product. The band disappears upon reaction with small amounts of water vapour as expected for isocyanates. Quantum yields for isocyanate formation by nucleobase ring cleavage in the α-position to the carbonyl group are ∼5 × 10−5 in the mononucleosides and up to 5 × 10−4 in the oligonucleotides. In the mixed oligonucleotides dG10/dC10 and dA10/dT10 the quantum yield of α-cleavage drops by a factor of 10 compared to the single oligonucleotides. Implications for DNA repair and photo-induced DNA–protein cross-linking via isocyanate reaction with NH2 groups of amino acids are discussed.

Graphical abstract: DNA photoreacts by nucleobase ring cleavage to form labile isocyanates

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Publication details

The article was received on 11 Apr 2013, accepted on 17 Jun 2013 and first published on 18 Jun 2013


Article type: Paper
DOI: 10.1039/C3CP51552D
Phys. Chem. Chem. Phys., 2013,15, 18371-18377

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    DNA photoreacts by nucleobase ring cleavage to form labile isocyanates

    L. Buschhaus, J. Rolf and K. Kleinermanns, Phys. Chem. Chem. Phys., 2013, 15, 18371
    DOI: 10.1039/C3CP51552D

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