Toxicology of Industrial Compounds

adducts are not viewed as particularly promutagenic. Nevertheless the N 7 -
atom of dG residues in DNA is a major target for adduction and the
detection of N 7 -dG adducts signals the production of adducts at other
(more critical) sites in DNA (vide supra).
In certain instances, a class of adducting moieties may possess a common
structural feature that can be exploited for immunoenrichment. For
example, a Mab has been raised against the major DNA adduct of benzo(a)
pyrene (r-7,t-8,t-9-trihydroxy-c-10-(N 2 -deoxyguanosylphosphate)-7,8,9,
10-tetrahydrobenzo(a)pyrene) in a collaborative study with Dr Baan’s
group. This Mab recognises DNA adducts formed by a broad range of
polycyclic aromatic hydrocarbons (PCAs) including benzo(a)pyrene (BP),
chrysene, benz(a)anthracene, 5-methylchrysene, picene and dibenz(a,h)
anthracene. It seems probable that this Mab recognises the common
trihydric alcohol structure produced when the reactive diol epoxides of
each of these polycyclic compounds reacts with nucleophilic centres in
DNA or other macromolecules. The fact that the Mab does not bind the
corresponding fluoranthene adduct is consistent with the spatial
environment of the hydroxyl groups in fluoranthene-DNA adducts which
is completely different from those generated from the other PCAs employed
in this study.
The performance of the Mab raised against the major BP-DNA adduct in
the enrichment of PCA-DNA adducts is being evaluated using the
immobilised Mab coupled to cyanogen bromide-activated Sepharose 4B.
Results obtained to date demonstrate that the immobilised Mab selectively
adsorbs the major BP-DNA adduct from DNA hydrolysates at abundances
below 1 adduct per 10 9 nucleotide units. Results with the other PCA-DNA
adducts are not yet available. However, the results obtained with the major
BP-DNA adduct underlines the potential of immunoenrichment technology
in the qualitative and quantitative analysis of adducts. Furthermore, such
results provide an incentive to pursue the development of class-specific
antibodies in order to permit or facilitate the identification of the chemical
initiators of human cancer.
Mercapturic acids
A.S.WRIGHT ET AL. 187
Qualitative analysis of mercapturic acids also provides a basis for
identifying human exposures to genotoxic chemicals (vide supra). However,
the available analytical procedures are complex and tend to lack specificity
and sensitivity. During the last dozen years we have undertaken a number
of studies aimed at developing compound- and class-specific antibodies to
facilitate the analysis of mercapturic acids.
Conventional approaches to generate antibodies to low molecular weight
(MW) organic chemicals involves the covalent attachment of the small
molecule (hapten) to a strongly antigenic protein, e.g. keyhole limpet