Photoinduced electron transfer and enhanced triplet yields in benzo[a]pyrene derivative-nucleic acid complexes and covalent adducts

Journal Article · Tue Jan 11 23:00:00 EST 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00080a008· OSTI ID:5153799

Shafirovich, V Y; Levin, P P; Kuzmin, V A ^[1]; Thorgeirsson, T E; Kliger, D S ^[2]; Geacintov, N E ^[3]

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1. New York Univ., NY (United States) Univ. of California, Santa Cruz, CA (United States)
2. Univ. of California, Santa Cruz, CA (United States)
3. New York Univ., NY (United States)

The carcinogenic and mutagenic benzo[a]pyrenediol epoxide derivative 7r,8t-dihydroxy-9t,10t-epoxy-7,8,9,-10-tetrahydrobenzo[a] pyrene (BPDE) binds via its C-10 position predominantly to the exocyclic amino group of guanine residues in native DNA. In such DNA adducts, the fluorescence of the pyrenyl moieties is strongly quenched by physicochemical interaction with the DNA bases. Using nanosecond time scale transient absorption techniques, products of the fluorescence quenching have been examined in two model systems in aqueous and polar organic solvents. The first is a monomeric, covalently linked (+)-trans-BPDE-N[sup 2]-2[prime]-deoxyguanosine adduct (BPDE-dG), the most abundant adduct when (+)-BPDE binds to native DNA; the second consists of mixtures of 7,8,9,10-tetrahydroxytetrahydrobenzo[a]pyrene (BPT) with dG, which was used to study the role of noncovalent interactions in solvents of different hydrophobicities. At moderate laser pulse energies ([le] 25 mJ/cm[sup 2]/pulse, 347 nm), the primary products of the fluorescence quenching reaction are pyrenyl residue triplet excited states, with greatly enhanced yields (by factors of 3-10 or more relative to the yields expected from simple intersystem crossing). The primary quenching reaction involves photoinduced electron transfer from dG to pyrenyl residues, followed by efficient recombination to form triplet excited states. 72 refs., 9 figs., 1 tab.

• OSTI ID: 5153799
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:1; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
AMINES
AROMATICS
AZAARENES
BENZOPYRENE
CARCINOGENS
CHEMICAL REACTIONS
COMPLEXES
CONDENSED AROMATICS
DNA ADDUCTS
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ENERGY LEVELS
EPOXIDES
EXCITED STATES
FLUORESCENCE
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROXY COMPOUNDS
ION PAIRS
LASER RADIATION
LUMINESCENCE
MULTIPLETS
MUTAGENS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PURINES
QUENCHING
RADIATIONS
RADICALS
TRIPLETS