Journal Article

<sup>32</sup>P-Postlabelling of diastereomeric 7-alkylguanine adducts of butadiene monoepoxide

Rajiv Kumar, Pavel Vodicka, Pertti Koivista, Kimmo Peltonen and Kari Hemminki

in Carcinogenesis

Volume 17, issue 6, pages 1297-1303
Published in print June 1996 | ISSN: 0143-3334
Published online June 1996 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/17.6.1297
32P-Postlabelling of diastereomeric 7-alkylguanine adducts
                    of butadiene monoepoxide

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The reaction of 3, 4-epoxy-1-butene (BMO) with deoxygu-anosine-3'-monophosphate (3'-dGMP) resulted in the formation of two pairs of diastereomeric 7-alkyl-3'-dGMP derivatives corresponding to two isomers C''-1 and C''-2. The T4 polynucleotide kinase-mediated phosphorylation with (γ-32P)-ATP showed preferential labelling of diastereo-mers of the C''-1 isomer. The diastereomers 1 and 2 of the C''-1 isomer had labelling efficiencies of 42%.However, the labelling efficiencies of diastereomers 3 and 4 of the C''-2 isomer were 11 and 10%, respectively.The 32P-postlabelling of BMO-modified DNA yielded four isomers in the ratio of 4: 4: 1: 1 with overall recoveries being 14%. The two isomers had a half-life of 270 min (C''-1 isomer) and 300 min (C''-2 isomer) which is in accordance with the stability predicted by other similar adduct experiments. The molecular modelling experiments showed more pronounced restricted rotation of butadiene residue in C''-2 isomers due to steric interaction between butadiene residue at N-7 and O6 atom of guanine than in C''-1 isomer. The butadiene residue also leads to steric overcrowding at 3′-phosphate in C''-2 isomer which probably restricts the access to the active site of T4 polynucleotide kinase.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

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