Styrene 7,8-oxide, which reacts preferentially at the N-7 position of guanine, yielded two pairs of diastereomers 7-(1'-hydroxy-2'-phenylethyl)-dGMP (the alpha-isomer) and 7-(2-hydroxy-2-phenylethyl)-dGMP (the beta-isomer) on reaction with deoxyguanosine-3'-monophosphate (3'-dGMP). The alpha- and beta-isomers were formed in the ratio 32:68. T4 polynucleotide kinase preferentially mediated labelling of diastereomers corresponding to the beta-isomer. The beta-diastereomers showed a labelling efficiency of 52%, whereas the alpha-isomers showed a labelling efficiency of 4%. Molecular modelling experiments showed intrinsic differences between the two isomers. The torsion angles of C8-N7-2'-Ar and C8-N7-2'-1' for the alpha-isomers were 149.9 degrees and -26.4 degrees, whereas the torsion angles of C-8-N7-1'-2' and N7-1'-2'-Ar for the beta-isomers were 105.3 degrees and 179.4 degrees. The consequent interatomic distance between one of the hydrogens on the alpha-carbon and the 3'-phosphate group on the sugar residue was 5.3 A in the alpha-isomer whereas the closest distance between the hydrogens attached to the alpha-carbon and 3'-phosphate group in the beta-isomer was 6.2 A. This arrangement probably leads to steric overcrowding at the 3'-phosphate group in alpha-isomers and these are less efficiently phosphorylated than beta-isomers. In in vitro styrene oxide-modified salmon testis DNA alpha- and beta-isomers of 7-alkylguanines were formed in the ratio 37:63. The recovery of two diastereomeric beta-isomers in a 32P-postlabelling assay was 14%, but one of the diastereomers was obtained in 3-fold greater yield than the second isomer.

• MeSH
• chemické modely MeSH
• deoxyguaninnukleotidy metabolismus   MeSH
• DNA metabolismus   MeSH
• epoxidové sloučeniny metabolismus   MeSH
• fosforylace MeSH
• karcinogeny metabolismus   MeSH
• radioizotopy fosforu MeSH
• stereoizomerie MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

The reaction of 3,4-epoxy-1-butene (BMO) with deoxyguanosine-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 [gamma-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 O(6) 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.

• MeSH
• adukty DNA analýza   biosyntéza   izolace a purifikace   MeSH
• deoxyguaninnukleotidy izolace a purifikace   metabolismus   MeSH
• DNA metabolismus   účinky léků   MeSH
• epoxidové sloučeniny farmakologie   metabolismus   MeSH
• fosforylace MeSH
• izotopové značení MeSH
• losos MeSH
• molekulární modely MeSH
• mutageny farmakologie   izolace a purifikace   metabolismus   MeSH
• poločas MeSH
• polynukleotid-5'-hydroxylkinasa metabolismus   MeSH
• radioizotopy fosforu MeSH
• stereoizomerie MeSH
• vazebná místa MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH