Phosphate, metal ions binding

Certain kinds of metal ions bind to the DNA double strands by an electrostatic interaction with the phosphate group(s) or by complex formation with the sugar moiety or the nucleic... 

Metal ions can attach themselves at two different types of sites on a polynucleotide—i.e., the phosphate and the donor groups on the bases. Some of the metal ions do indeed bind at one site, and some metal ions at the other. Those binding to the phosphate will promote the cleavage of the phosphate bond, whereas metal ions binding on the base will inhibit such cleavage in a manner that illustrates one of Dr. Jones points very well. 

Reactions with electrophilic reagents. Reactions of nucleic acids with the simplest electrophile, the proton, have been considered in Section A2. Somewhat similar are the reactions by which metal ions bind at many sites on both the bases and the phosphate groups of the backbone.550... 

The relationship between the sites that bind metal ions has also been studied,1319 using 31P and 113Cd NMR spectroscopy these techniques have provided valuable information on the influence of metal-ion binding, cooperativity and phosphate binding. ... 

Templeton et al. (2002a) used a combination of Pb Lm-XAFS and pXANES spectroscopy and transmission electron microscopy to show that B. cepacia causes biomineralization of Pb(II) in the form of highly insoluble pyromorphite at ( ) concentrations well below supersaturation with respect to pyromorphite. The phosphate in these minimal medium experiments is though to be provided by B. cepacia, and the pyromorphite forms on the outer cell membrane of B. cepacia. These types of studies are beginning to provide unique information on how microbial biofilms affect metal sorption processes at mineral surfaces, which is essential for understanding the transport and bioavailability of toxic metal ions in natural systems where such biofilms exist. They are also allowing quantitative evaluation of the competition between NOM (or biofilms) and the mineral substrates they coat for metal ion binding. 

Sternlicht, Jones, and Kustin (5) have found evidence that the metal ion binds, in such complexes, to the base of one molecule and the phosphate of another molecule. Models demonstrate that our NMR data can be explained if there is a binuclear complex in which each metal ion is bound to the base of one molecule and to the phosphate of another (Figure 9). 

---