TY - JOUR
T1 - Properties of covalent benzo[a] pyrene diol eporide-dna adducts investigated by fluorescence techniques
AU - Geacintov, Nicholas E.
AU - Zinger, David
AU - Ibanez, Victor
AU - Santella, Regina
AU - Grunberger, Dezider
AU - Harve, Ronald G.
N1 - Funding Information:
We wish to thank Dr I.B.Wrinstein for valuable discussions and suggestions concerning this work. The generous assistance of Dr J.C.Sutherland and his group in carrying out the synchrotron excitation experiments is gratefully acknowledged. This research was in part carried out at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the Department of Energy, Division of Materials Sciences and Division of Chemical Sciences (DOE Contract No. DE-AC02-76CH00016). This work was supported by Grants CA-20851 (N.E.G.), CA-21111 (D.G.) and CA-31696 (R.S.), awarded by the National Cancer Institute, Department of Health and Human Services, and by an American Cancer Society Grant BC-132 (R.G.H.) at the University of Chicago. We are pleased to acknowledge equipment grants from the Camille and Henry Dreyfus Foundation, Inc., the National Science Foundation (Grant number PCM-8108289), and the New York University Research Challenge Fund, which made this work possible.
PY - 1987/7
Y1 - 1987/7
N2 - The spectroscopic absorption and fluorescence properties of adducts derived from the covalent binding of (±)trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,l0-tetrahydrobenzo[a]pymne (BPDE) to DNA are re-examined in view of conflicting interpretations regarding the Coaformations of these adducts which currently exist in the literature. The fluorescence decay profiles were accurately determined utilizing synchrotron-pulsed light source excitation and the time-correlated single photon counting technique. The coaformational properties of the adducts were probed by determining their accessibilities to acrylamide, a known fluorescence quencher, and by comparing the accessibilities of the BPDE-DNA adducts with those of known model systems with intercalative, partially intercalative and minor groove binding conformations. In contrast toanyofthesemodelsystems,tkfhmesmmofthearomahic pyrenyl residues in the covalent BPDE - DNA ad- exhibit significant sensitivity to acrylamide, suggesting that these residues are located at binding sites with significant solvent exposure. A quantitative analysis of the acrylamide fluorescence quenching according to a dynamic Stem-Volmer quenching model suggests the following characteristics: the major (65%) component (1.4 ns lifetime) is characterized by significant exposure to the sotvent environment; the second component (6-7 ns lifetime) can be subdivided into a solvent-accessible and a solvent-inaccessible component, the inaccessible fraction being attributed to minor adducts, possibly with a quasi-intercalative conformation. The amplitude of the third, long-lived (200-ns) component is variable; it arises from the photochemical decomposition of the adducts which gives rise to tetraols (7,8,9,1O-tetrahydro-tetrahydroxybenzo[a]pyrene). The variable content of these degradation products accounts for most discrepancies in the fluorescence properties of the covalent BPDE-DNA adducts previously reported.
AB - The spectroscopic absorption and fluorescence properties of adducts derived from the covalent binding of (±)trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,l0-tetrahydrobenzo[a]pymne (BPDE) to DNA are re-examined in view of conflicting interpretations regarding the Coaformations of these adducts which currently exist in the literature. The fluorescence decay profiles were accurately determined utilizing synchrotron-pulsed light source excitation and the time-correlated single photon counting technique. The coaformational properties of the adducts were probed by determining their accessibilities to acrylamide, a known fluorescence quencher, and by comparing the accessibilities of the BPDE-DNA adducts with those of known model systems with intercalative, partially intercalative and minor groove binding conformations. In contrast toanyofthesemodelsystems,tkfhmesmmofthearomahic pyrenyl residues in the covalent BPDE - DNA ad- exhibit significant sensitivity to acrylamide, suggesting that these residues are located at binding sites with significant solvent exposure. A quantitative analysis of the acrylamide fluorescence quenching according to a dynamic Stem-Volmer quenching model suggests the following characteristics: the major (65%) component (1.4 ns lifetime) is characterized by significant exposure to the sotvent environment; the second component (6-7 ns lifetime) can be subdivided into a solvent-accessible and a solvent-inaccessible component, the inaccessible fraction being attributed to minor adducts, possibly with a quasi-intercalative conformation. The amplitude of the third, long-lived (200-ns) component is variable; it arises from the photochemical decomposition of the adducts which gives rise to tetraols (7,8,9,1O-tetrahydro-tetrahydroxybenzo[a]pyrene). The variable content of these degradation products accounts for most discrepancies in the fluorescence properties of the covalent BPDE-DNA adducts previously reported.
UR - http://www.scopus.com/inward/record.url?scp=0023189687&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023189687&partnerID=8YFLogxK
U2 - 10.1093/carcin/8.7.925
DO - 10.1093/carcin/8.7.925
M3 - Article
C2 - 3109756
AN - SCOPUS:0023189687
VL - 8
SP - 925
EP - 935
JO - Carcinogenesis
JF - Carcinogenesis
SN - 0143-3334
IS - 7
ER -