The stereospecific binding of monoclonal antibody (mAb) 8E11 to anti-benzo(a)pyrene diol epoxide (BPDE)-dG adducts in single nucleoside, long oligonucleotide, and genomic DNA were quantitatively evaluated using noncompetitive and competitive capillary electrophoresis (CE) immunoassays. Two single-stranded TMR-BPDE-90 mers containing a single anti-BPDE-dG adduct with defined stereochemistry and a fluorescent label at 5'-end were used as fluorescent probes for competitive CE immunoassay. To quantitatively evaluate the binding affinity through competitive CE immunoassays, a series of equations were derived according to the binding stoichiometry. The binding of mAb 8E11 to trans-(+)-anti-BPDE-dG displays strongest affinity (K(b): 3.57 x 10(8) M(-1)) among all four investigated anti-BPDE-dG mononucleoside adducts, and the cis-(-)-anti-BPDE-dG displays lowest affinity (K(b): 1.14 x10(7) M(-1)). The binding of monoclonal antibody (mAb) 8E11 to BPDE-dG adducts in long DNA (90 mer) preferentially forms the complex with a stoichiometry of 1:1, and that mAb 8E11 displays a slightly higher affinity with trans-(+)-anti-BPDE-90 mers (K(b): 6.36+/-0.54 x 10(8)M(-1)) than trans-(-)-anti-BPDE-90 mers (K(b): 4.52+/-0.52 x 10(8) M(-1)). The mAb 8E11 also displays high affinity with BPDE-dG adducts in genomic DNA (K(b): 3.74 x 10(8) M(-1)), indicating its promising applications for sensitive immuno-detection of BPDE-DNA adducts in genomic DNA.
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