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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