Copper complexes nucleotides

ORD spectra of copper complexes with a variety of proteins and peptides give conformational as well as quantitative information on the metal binding (9, 10, 35). This method also has been successfully applied to study metal complexes with nucleotides (53, 70). 

Chelex-100 (Whatman) resin was suspended in 1 M CuCl2 overnight, washed repeatedly in water and suspended in 1 N ammonia overnight. A column (0.9 x 45 cm) was packed with a small volume of non-CuCl2 treated resin at the bottom followed by the copper complexed resin above. After washing the column, the nucleic acid components were loaded in a small volume of water and eluted with water (nucleotides followed by weakly basic nucleosides), 1 N ammonia (other nucleosides) and/or 2.5 N ammonia (bases). The nucleotides are not bound by the column and so are not fractionated. The nucleosides and bases are, however, well fractionated. Several minor components are well separated. The method is relatively quick and the eluants are volatile. 

Oyoshi T, Sugiyama H. Mechanism of DNA strand scission induced by (1,10-phenan-throline)copper complex m or direct DNA cleavage is not through l ,2 -dehydro-nucleotide intermediate nor beta-ehmination of forming ribonolactone. J Am Chem Soc. 2000 122 6313-6314. 

Mitochondria contain ubiquinone (also known as coenzyme Q), which differs from plastoquinone A (Chapter 5, Section 5.5B) by two methoxy groups in place of the methyl groups on the ring, and 10 instead of 9 isoprene units in the side chain. A c-type cytochrome, referred to as Cyt Ci in animal mitochondria, intervenes just before Cyt c a h-type cytochrome occurring in plant mitochondria is involved with an electron transfer that bypasses cytochrome oxidase on the way to 02. The cytochrome oxidase complex contains two Cyt a plus two Cyt a3 molecules and copper on an equimolar basis with the hemes (see Fig. 5-16). Both the Fe of the heme of Cyt a3 and the Cu are involved with the reduction of O2 to H20. Cytochromes a, >, and c are in approximately equal amounts in mitochondria (the ratios vary somewhat with plant species) flavoproteins are about 4 times, ubiquinones 7 to 10 times, and pyridine nucleotides 10 to 30 times more abundant than are individual cytochromes. Likewise, in chloro-plasts the quinones and the pyridine nucleotides are much more abundant than are the cytochromes (see Table 5-3). 

Inorganic Derivatives.- The ring phosphorus sugar analogue (7), the 5-diphenylphosphlno-2-oxablcyclo[3.2.0]heptane-3,4-diol derivative (8), and two copper-nucleotide complexes Ca[Cu(guanosine... 

In contrast to Mg + and Mn +, which stabilize secondary structures in DNA and RNA, Cu + destabilizes DNA and RNA double helices, and this is attributed to the ability of copper to bind to the nucleic acid bases. Chao and Kearns have recently explored the possibility that this binding, as detected by electron and nuclear magnetic resonance spectroscopy, might be used to probe certain structural features of nucleic acid molecules, such as the looped out regions of tRNAs. The nature of the Cu complexes formed with nucleosides and nucleotides varies with the specific nucleic acid derivatives used and also the pH. Thus, in the pH range 8.5—10.0, copper forms a water-soluble complex with the ribose OH groups of the ribonu-cleosides and 5 -ribonucleotides, but these complexes cannot form with any of the deoxynucleosides or the 2 - and 3 -ribonucleotides. It is suggested that copper(ii) could stabilize unusual polynucleotide structures or interactions in certain enzymatic systems the latter could, for example, be responsible for translational errors in the RNA,DNA polymerase system which are known to be induced by transition metals. 

Volume 1 Simple Complexes Volume 2 Mixed-Ligand Complexes Volume 3 High Molecular Complexes Volume 4 Metal Ions as Probes Volume 5 Reactivity of Coordination Compounds Volume 6 Biological Action of Metal Ions Volume 7 Iron in Model and Natural Compounds Volume 8 Nucleotides and Derivatives Their Ligating Ambivalency Volume 9 Amino Adds and Derivatives as Ambivalent Ligands Volume 10 Carcinogenicity and Metal Ions Volume 11 Metal Complexes as Anticancer Agents Volume 12 Properties of Copper Volume 13 Copper Proteins... 

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