PMID- 6815256
OWN - NLM
STAT- MEDLINE
DCOM- 19830107
LR  - 20190913
IS  - 0165-022X (Print)
IS  - 0165-022X (Linking)
VI  - 6
IP  - 4
DP  - 1982 Sep
TI  - Probing the microenvironment of benzo[a]pyrene diol epoxide-DNA adducts by 
      triplet excited state quenching methods.
PG  - 269-81
AB  - Triplet flash photolysis techniques, coupled with quenching of the triplets by 
      molecular oxygen, are utilized as probes of the microenvironment of polycyclic 
      aromatic molecules bound covalently and non-covalently to DNA. The triplet-oxygen 
      quenching properties of the following adducts in aqueous solutions at 25 +/- 1 
      degrees C were investigated: covalent adducts derived from the reaction of 
      (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9, 
      10-tetrahydrobenzo[a]pyrene (BaPDE) and of 
      (+/-)-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BaPE) with DNA, and 
      non-covalent intercalation complexes of acridine orange (AO) and DNA. In all 
      cases the quenching follows the Stern-Volmer quenching law with a quenching 
      constant of KTO2 approximately equal to 10(9) M-1 X S-1 for the covalent 
      BaPDE-DNA and BaPE-DNA complexes in aqueous solution. This value of KTO2 is 
      characteristic of free molecules (not bound to DNA) and indicates that the pyrene 
      chromophore is totally accessible to oxygen, and is thus not located at an 
      intercalation-type of binding site in these covalent adducts. In contrast, the 
      AO-DNA complexes are characterized by values of KTO2 approximately equal to 10(8) 
      M-1 X S-1 indicating that the intercalated AO molecules are about ten times less 
      accessible to molecular oxygen than free AO molecules. The KTO2 values for the 
      covalent BaPDE-DNA and BaPE-DNA adducts decrease when the DNA concentration is 
      increased in the 1 X 10(-4)-3 X 10(-3) M range (expressed in nucleotide 
      concentration). This effect is attributed to intermolecular DNA-DNA interactions 
      in which segments of adjacent DNA molecules tend to cover the pyrene chromophores 
      on other strands, thus decreasing their accessibility to oxygen. In contrast the 
      values of KTO2 for the non-covalent AO-DNA intercalation complexes are 
      independent of DNA concentration, as expected for interior binding sites.
FAU - Poulos, A T
AU  - Poulos AT
FAU - Kuzmin, V
AU  - Kuzmin V
FAU - Geacintov, N E
AU  - Geacintov NE
LA  - eng
GR  - R01 CA20851/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - Netherlands
TA  - J Biochem Biophys Methods
JT  - Journal of biochemical and biophysical methods
JID - 7907378
RN  - 0 (Benzopyrenes)
RN  - 0 (Carcinogens)
RN  - 0 (Mutagens)
RN  - 55097-80-8 (7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide)
RN  - 9007-49-2 (DNA)
RN  - F30N4O6XVV (Acridine Orange)
RN  - S88TT14065 (Oxygen)
SB  - IM
MH  - 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
MH  - Acridine Orange/metabolism
MH  - *Benzopyrenes
MH  - Carcinogens
MH  - Chemical Phenomena
MH  - Chemistry
MH  - *DNA
MH  - Fluorescence
MH  - Kinetics
MH  - Mutagens
MH  - Oxygen
MH  - Photolysis
MH  - Spectrophotometry
EDAT- 1982/09/01 00:00
MHDA- 1982/09/01 00:01
CRDT- 1982/09/01 00:00
PHST- 1982/09/01 00:00 [pubmed]
PHST- 1982/09/01 00:01 [medline]
PHST- 1982/09/01 00:00 [entrez]
AID - 0165-022X(82)90009-4 [pii]
AID - 10.1016/0165-022x(82)90009-4 [doi]
PST - ppublish
SO  - J Biochem Biophys Methods. 1982 Sep;6(4):269-81. doi: 
      10.1016/0165-022x(82)90009-4.