Synthesis and duplex-forming properties of a nonanucleotide containing an N6-deoxyadenosine adduct of a bay-region diol epoxide
作者:Mahesh K. Lakshman、Jane M. Sayer、Haruhiko Yagi、Donald M. Jerina
DOI:10.1021/jo00043a012
日期:1992.8
A protected derivative, corresponding to the adduct derived from trans opening of (+/-)-1-alpha,2-beta-dihydroxy-3-beta,4-beta-epoxy-1,2,3,4-tetrahydrophenanth rene (in which the benzylic hydroxyl and epoxide groups are trans, Phenanthrene diol epoxide-2) by the exocyclic amino group of 2-deoxyadenosine (dA), has been synthesized by couPling (+/-)-1-alpha,2-beta,3-beta-trihydroxy-4-alpha-amino-1,2,3,4-tetrahydrophenan threne with a disilyl derivative of 6-fluoro dA. The resulting pair of diastereomeric adducts was easily separated by HPLC, and the absolute configuration of each diastereomer was assigned from its CD spectrum by analogy to known tetrahydrophenanthrene analogs. The structures of these adducts were confirmed by comparison of the NMR spectra of the derived pentaacetates with those obtained for the corresponding compounds prepared from dAMP and phenanthrene diol epoxide-2. Acetylation of the free hydroxyl groups, desilylation of the sugar, 5'-O-(4,4'-dimethoxytrityl) protection, and generation of a 3'-O-[(NN-diisopropylamino)(beta-cyanoethoxy)phosphine] provided an intermediate that was incorporated, using modified solid-phase DNA synthesizer methodology, into the oligonucleotide d(GGT CA*C GAG) comprising codons 60-62 of the human K-ras b proto-oncogene sequence. The effect of an adduct on the T(m) values for duplexes formed by this nonamer with complementary strands in which the residue opposite the modified dA is T or either of the "mismatched" purine nucleosides dA or dG was determined. Replacement of T with dG opposite the modified dA has little or no effect on T(m), whereas replacement of T with dA decreases the T(m) of the modified duplex by 9-degrees-C.