Nucleic acids Metal-binding

In the biologically relevant, usually monodentate, ademne " " (238) and related ligands (239-241), it is often difficult in deciding if binding takes place at the N-1 or N-7 sites, and it is possible that the binding position for adenine may be metal ion specific Ni°, Cu , Co°, Cd at N-7 Zn at both Hg and at N-1 (see Nucleic Acid-Metal Ion Interactions). 

Biomineralization Calcium-binding Proteins Metal Ion Toxicity Metal-mediated Protein Modification Metalloreg-ulation Nucleic Acid-Metal Ion Interactions Nutritional Aspects of Metals Trace Elements. 

Nucleic acids usually bind alkali monovalent metal ions only in an atmospheric manner (in which the M+-phosphate distance is larger than 7 For polyvalent metal ions,... 

Apart from the understanding of the mechanism of anti-tumour action of cis-[PtCl2(NH3)2l a major interest in the area of nucleic acid-metal ion interactions is the possibility of sequence determination, using specific binding of metal complexes. 

In addition to serving structural and modulating roles in proteins which bind nucleic acids, metal ions also appear to be essential to the functioning of various complex enzymes that act on nucleic acids. At this stage our understanding of the participation of the metal ion in the catalytic chemistry of these enzymes is somewhat sketchy, and we are relying more on our current understanding of the... 

DeRose VJ (2009) Characterization of nucleic acid-metal Ion binding by spectroscopic techniques. In Hud NV (ed) Nucleic acid-metal ion interactions. The Royal Society of Chemistry, London... 

Two aspects of nanoparticles immobilization on biopolymers should be mentioned. First, most of the heavy metals bind simultaneously to several protein macroligands with a specific spatial environment and conformation. Triple complexes may also form composed of protein/metal/nucleic acid (metal = Au, Pt, Pd). Perhaps the presence of these structures provides the anticarcinogenic effect achieved on introduction of these metals into organisms. Second, heavy metals, such as Au(T), react with native Zn-, Cd-, and Co-thioneins by replacing selectively Zn and even Cd when added in excess. This process is characterized by only minimal changes in the protein conformation. 

Metal complexes of nucleic acid derivatives and nucleotides binding sites and structures. L. G. Marzilli, Adv. Inorg. Biochem., 1981, 3, 48-85 (138). 

Stereoselectivity in the binding of transition metal chelate complexes to nucleic acid constituents bonding and non-bonding effects. L. G. Marzilli and T. J. Kistenmacher, Acc. Chem. Res., 1977, 10,146-152 (29). 

The theory and application of this fluorescence method have been discussed in detail by LePecq and others (3,8). The assay requires that there is sufficient ionic strength to minimize ionic binding (e.g., O.IM sodium chloride), that the pH is 4-10, that no heavy metals are present, that the fluorescence is not enhanced on binding to other excipients (e.g., proteins) and that at least portions of the nucleic acids are not complexed. These requirements can usually he met when dealing with recombinant products in some cases the samples must he manipulated to create the appropriate conditions. In the intercalative method of dye binding, proteins rarely interfere with the assay, and procedures have been developed to remove the few interferences they may cause (e.g., the use of heparin or enzymatic digestion of the protein 9). 

The examples just presented give initial impressions of how DNA can be utilized as a template in the synthesis of nanometric and mesoscopic aggregates. However, the studies emphasize the importance of fundamental research on the interaction between DNA and the various binders, such as metal and organic cations. Of particular importance are the consequences of binding events on the structure and topology of the nucleic acid components involved. 

Copper is an essential trace element. It is required in the diet because it is the metal cofactor for a variety of enzymes (see Table 50—5). Copper accepts and donates electrons and is involved in reactions involving dismu-tation, hydroxylation, and oxygenation. However, excess copper can cause problems because it can oxidize proteins and hpids, bind to nucleic acids, and enhance the production of free radicals. It is thus important to have mechanisms that will maintain the amount of copper in the body within normal hmits. The body of the normal adult contains about 100 mg of copper, located mostly in bone, liver, kidney, and muscle. The daily intake of copper is about 2—A mg, with about 50% being absorbed in the stomach and upper small intestine and the remainder excreted in the feces. Copper is carried to the liver bound to albumin, taken up by liver cells, and part of it is excreted in the bile. Copper also leaves the liver attached to ceruloplasmin, which is synthesized in that organ. 

Maes BUW (2006) Transition-Metal-Based Carbon-Carbon and Carbon-Heteroatom Bond Formation for the Synthesis and Decoration of Heterocycles. 1 155-211 Maiti M, Kumar GS (2007) Protoberberine Alkaloids Physicochemical and Nucleic Acid Binding Properties. lO. 155-210... 

The initial hurdle to overcome in the biosensor application of a nucleic acid is that involving its stable attachment on a transducing element which commonly includes a metallic electrode. In the first part of this chapter, we wish to introduce our approach for DNA immobilization (Scheme 1). A detailed characterization of the immobilization chemistry is also presented. In the second part, we follow the development of work from our laboratory on chemical sensor applications of the DNA-modified electrode involving a biosensor for DNA-binding molecules and an electrochemical gene sensor. 

Another way in which Pt could bind to DNA is through the formation of intercalation compounds. The parallel here is with the hydrocarbon carcinogens and the nucleic acid stains, the acridines. It has been shown that metal chelates will form this same type of jt-complex. For example, palladium oxinate will form exactly the same type of -complexes as anthracene (88). 

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