Magnesium ions, interactions with

Magnesium ions interact with radical ions in aprotic media, which may influence the course of the reaction in some cases Mg" " also stabilizes the product and thereby helps avoiding unwanted further reactions [458,459]. 

The most important point is that this procedure provides a reliable and effective way for dealing with metal ion interactions with nucleotides. By maintaining the free magnesium ion at a single fixed concentration, the experimenter avoids any chance of uncontrolled variation in the [MgATp2-]/[ATP -j ratio. 

In some kinases, such as nucleoside diphosphate kinase, " an intermediate step is the phosphoryl transfer to a group belonging to the enzyme, as happens in ATPase and as was discussed in detail for alkaline phosphatase (Section V.B). In other kinases the phosphoryl transfer occurs directly from the donor to the acceptor in a ternary complex of the enzyme with the two substrates.Often metal ions like magnesium or manganese are needed. These ions interact with the terminal oxygen of the ATP molecule, thus facilitating the nucleophilic attack by the acceptor. The metal ion is often associated with the enzyme. For mechanistic schemes, see the proposed mechanism of action of alkaline phosphatase, especially when a phosphoryl enzyme intermediate is involved. 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

Bates et al. reported the construction and characterization of a gold nanoparticle wire assembled using Mg -dependent RNA-RNA interactions for the future assembly of practical nanocircuits [31]. They used magnesium ion-mediated RNA-RNA loop-receptor interactions, in conjunction with 15 nm or 30 nm gold nanoclusters derivatized with DNA to prepare self-assembled nanowires. A wire was deposited between lithographically fabricated nanoelectrodes and exhibited non-linear activated conduction by electron hopping at 150-300 K (Figure 16). 

Since many ion exchange columns exhibit mixed-mode interactions with analytes, factor analysis has been found to be useful in optimization.84 A 3-year, comprehensive review of inter-laboratory errors in determinations of the anions chloride, nitrate, and sulfate and the cations sodium, potassium, magnesium, and calcium suggested that multipoint calibration is essential and nonlinear calibration desirable.102 The need for nonlinear calibration was confirmed by an extended quality assurance study of chloride, sulfate, and nitrate in rainwater.103... 

Aich P, Dasgupta D (1990) Role of Mg(ll) in the Mithramycin-DNA interaction evidence for two types of Mithramycin-Mg(II) complex. Biochem Biophys Res Commun 173 689-696 Aich P, Dasgupta D (1995) Role of magnesium ion in mithramycin-DNA interaction binding of mithramycin-Mg + complexes with DNA. Biochemistr 34 1376-1385 Aich P, Sen R, Dasgupta D (1992a) Interaction between antitumor antibiotic Chromomycin A3 and Mg(ll) 1. Evidence for the formation of two types of Chromomycin A3-Mg(ll) complexes. Chem Biol Interact 83 23-33... 

Aich P, Sen R, Dasgupta D (1992b) Role of magnesium ion in the interaction between chromomycin A3 and DNA binding of chromomycin A3 — Mg + complexes with DNA. Biochemistry 31 2988-2997 Akman SA, Doroshow JJH, Thomas G, Burke J, Dizdaroglus M (1992) DNA base modifications induced in isolated human chromatin by NADH de hydrogenase-catalyzed reduction of doxorubicin. Biochemistry, 31 3500-3506... 

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