32P-postlabelling of diastereomeric 7-alkylguanine adducts of butadiene monoepoxide.
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.
Kumar
R
R
Center for Nutrition and Toxicology, Karolinska Institute, Huddinge, Sweden.
Vodicka
P
P
Koivisto
P
P
Peltonen
K
K
Hemminki
K
K
D000818:Animals; D001665:Binding Sites; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D018736:DNA Adducts / Q000032:analysis / Q000096:biosynthesis / Q000302:isolation & purification; D003848:Deoxyguanine Nucleotides / Q000302:isolation & purification / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism* / Q000494:pharmacology; D006207:Half-Life; D007553:Isotope Labeling; D008297:Male; D008958:Models, Molecular; D009153:Mutagens / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011116:Polynucleotide 5'-Hydroxyl-Kinase / Q000378:metabolism; D012474:Salmon; D013237:Stereoisomerism
D018736:DNA Adducts; D003848:Deoxyguanine Nucleotides; D004852:Epoxy Compounds; D009153:Mutagens; D010761:Phosphorus Radioisotopes; C024370:3,4-epoxy-1-butene; C034009:2'-deoxyguanosine 3'-phosphate; D004247:DNA; D011116:Polynucleotide 5'-Hydroxyl-Kinase