Heavy metal nucleotide interactions 14. raman difference spectrophotometric studies of competitive reactions in mixtures of 4 nucleotides with the electrophiles methyl mercury ii per chlorate cis di methyl gold iii per chlorate di chloro ethylene di ammine palladium ii trans di chloro di ammine palladium ii cis di chloro di ammine platinum ii trans di chloro di ammine platinum ii tetra mu acetato di rhodium ii and aquo penta ammine cobalt iii per chlorate factors governing selectivity in th

Moller, M.R.; Bruck, M.A.; O'connor, T.; Armatis, F.J.Jr ; Knolinski, E.A.; Kottmair, N.; Tobias, R.S.

Journal of the American Chemical Society 102(14): 4589-4598

1980


ISSN/ISBN: 0002-7863
Accession: 005552174

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Abstract
Competitive reactions of each of the electrophiles H3CHgII, cis(H3N)2PtII, trans-(H3N)2PtII, enPdII (en = ethylenediamine), trans-(H3N)2 PdII, cis-(H3C)2AuIII, Rh2(OOCCH3)4 and (H3N)5COIII with a mixture of 20 mM 5'-GMP, 20 mM 5'-CMP, 30 mM 5'-AMP and 30 mM 5'-UMP were studied at pH 7, 25.degree. C, using Raman perturbation difference spectroscopy to establish whether there is selectivity in the metal binding to the nuclei acids. Methylmercury(II) shows high selectivity for attack at N.sbd.H bonds and binds to UMP N(3) when 0 < rt (total metal:total phosphate) .ltoreq. 0.3. For 0.3 < rt .ltoreq. 0.8 binding st at N(1) of GMP, and when rt > 0.7 reaction also occurs with CMP, N(3). Cis- and trans-(H3N)PtII react with GMP at low rt values, but coordination is at N(7) and no proton loss from the ligand occurs. The cis isomer is unique in that it exhibits complete selectivity for the 2 purines, GMP and AMP, when 0 > rt .ltoreq. 0.3. The trans isomer shows less affinity for AMP. Intermediate behavior is exhibited by enPdII, trans-(H3N)2PdII and cis-(H3C)2AuIII, which react with purines and pyrimidines and both at ring N and N.sbd.H bonds. Reaction is most extensive with trans-(H3N)2PdII and least with cis-(H3C)2AuIII. Reactions of the diammineplatinum(II) electrophiles at low rt values are kinetically controlled. As substitutions at the metal center become faster, the product distributions shift toward that observed for H3CHgII where thermodynamic control obtains. The rhodium(II) acetate dimer behaves entirely differently from the other 2nd and 3rd-row transition metals and causes almost no perturbation of the nucleotide vibrations upon reaction. The presence of 2 intense bands involving Rh-Rh stretching shows that the cluster remains intact. The 1st row transition metal electrophile (H3N)5CoIII at rt = 0.2 gives no measurable perturbation of the base or phosphate vibrations and appears to form outer-sphere complexes.