Laser pulse-induced photochemical strand cleavage of site-specifically and covalently modified (+)-anti-benzo[a]pyrene diol epoxide-oligonucleotide adducts

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Chemical Research in Toxicology

DOI:https://doi.org/10.1021/tx00045a011· OSTI ID:502033

Li, Bin; Mao, Bing; Liu, Tong-Ming ^[1]

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1. New York Univ., NY (United States); and others

The specificity of the laser pulse-induced photocleavage method for detecting the sites of covalent binding of benzo[a]-pyrene diol epoxide in DNA was investigated using site-specifically modified oligonucleotide duplexes d(CTCACAT[G*]TACACTCT){center_dot}d(GAGAGTGTACATGTGA), where [G*] is the adducted guanine residue (+)-trans-anti-BPDE-N{sup 2}-dG (anti-BPDE = 7{beta}, 8{alpha}-dihydroxy-9{alpha}, 10{alpha}-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene). The appropriate oligonucleotide strands were {sup 32}P-end-labeled, and the duplexes were irradiated with a pulse train of 355 nm Nd:YAG laser pulses ({approximately}300 mW/cm{sup 2}). The products of the photocleavage reaction were analyzed by denaturing gel electrophoresis. The major observed products included the intact oligonucleotide strand that had lost the BPDE residue, and shorter oligonucleotide fragments arising from strand that had lost the BPDE residue, and shorter oligonucleotide fragments arising from strand scission at the BPDE-modified guanine residue and at nearby flanking bases. Photocleavage at the BPDE-modified G is dominant ({approx}50 {plus_minus} 5% of the sum of all of the shorter oligonucleotide fragments), and cleavage extends to at least 4 bases on the 5{prime}-side, and 7 bases on the 3{prime}-side of the BPDE-modified G residue; the probability of cleavage diminishes with increasing distance from the modified G residue. On the unmodified of cleavage diminishes with increasing distance from the modified G residue. On the unmodified complementary strand, nonspecific strand cleavage is also observed, but the probability of cleavage is {ge}20 times smaller than at the BPDE-modified G residue on the modified strand. 50 refs., 4 figs.

• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-86ER60405
• OSTI ID: 502033
• Journal Information: Chemical Research in Toxicology, Journal Name: Chemical Research in Toxicology Journal Issue: 3 Vol. 8; ISSN 0893-228X; ISSN CRTOEC
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
BENZOPYRENE
CLEAVAGE
DNA ADDUCTS
ELECTROPHORESIS
EPOXIDES
GENETIC EFFECTS
GLYCOLS
GUANINE
IRRADIATION
LABELLED COMPOUNDS
MUTATIONS
PHOSPHORUS 32
STRAND BREAKS