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Spectral changes associated with structural modification of polyinosinic acid (polyI) in relation to alkali metal ion concentration, temperature and pH are studied using vibrational infrared absorption and vibrational circular dichroism. The results show that increase in temperature or pH at low alkali ion concentration results in disruption of the quadruplex structure.

The effects of changing the nucleotide 5' to the cleavage site on metal ion reactivity preference in the genomic and antigenomic hepatitis delta virus (HDV) ribozymes are examined. The results have provided evidence that a divalent metal ion, which is located close to the cleavage site, affects the rate of ribozyme cleavage.

The function of metal ions and the catalytic mechanism of dipeptide formation are investigated through kinetic studies and pH dependence experiments that are performed in the TR 158-catalyzed reaction. It is suggested that M[g.sup.2+] and L[i.sup.+] function are similar in the ribozyme-catalyzed dipeptide synthesis.

Ferrochelatase enzyme metal binding residues and the location of the active site were explored by using the various biochemical and biophysical methods. The results strongly suggested that the insertion of a metal ion into protoporphyrin IX by ferrochelatase occurs from a metal binding site represented by His183 and Glu264.

A molecular dynamics investigation of guanine quadruple helices based on classical force fields is done by studying the dependence of the helical conformation on different compositional factors like lengths of the G4 wire, the incorporation into the helix channel of alkali ions of various species and in varying amount. The empirical outcomes indicate that monovalent alkali cations help the stability of the quadruplex arrangement against disruption on the few nanoseconds time scale in the order of increasing van der Waals radius.

In this paper, we describe the synthesis and characterization of analytical properties of fluorescence-based zinc ion-sensing glass slides and their application in monitoring zinc ion release from beta pancreatic cells in cell cultures. To fabricate the sensors, the zinc ion indicator ZnAF-2 {6-[N-[N',N'-bis(2-pyridinylmethyl)-2-aminoethyl]amino3', 6'-dihydroxyspiro[isobenzofuran-1(3H),9'-[9H]xan-thene]-3-one} was modified to include a sufficiently long linking aliphatic chain with a terminal carboxyl functional group. The recently synthesized ZnAF-2 zinc ion indicator provided high zinc ion selectivity in physiological solutions containing millimolar levels of calcium and other possible interfering cations. The carboxyl-modified ZnAF-2 was conjugated to the activated surface of glass slides, which then served as zinc ion sensors. It was possible to grow pancreatic cells directly on the zinc-sensing glass slide or on a membrane placed on these glass slides. The sensors were used to monitor zinc ion release events from glucose-stimulated pancreatic cells. The study showed that the zinc ion sensors responded effectively to the release of zinc ions from pancreatic cells at the nanomolar level with high selectivity and rapid subsecond response time.

The various physicochemical factors that influence the flux of carrier-transported metal ions through permeation liquid membranes (PLM) are studied systematically. Understanding PLM behavior is important (i) to optimize the application of PLM as metal speciation sensors in environmental media and (ii) because PLM may serve as bioanalogical devices that help to elucidate the environmental physicochemical processes occurring at the surface of biological membranes. Diffusion of free and complexed metal ions in solution, as well as diffusion of the metal carder complex in the membrane, is considered. The respective roles of diffusion layer thickness, ligand concentration, complex stability, carder concentration, and membrane thickness are studied experimentally in detail and compared with theory, using various labile complexes, namely, Pb(II)--diglycolate, Cu(II)--diglycolate, and Cu(II)--N-(2-carboxyphenyl)glycine. Conditions where either membrane diffusion or solution diffusion is rate limiting are clearly discriminated. It is shown in particular, that, by tuning the carder concentration or membrane thickness, either the free metal ion concentration or the total labile metal species are measured. PLM can thus be used to determine whether models based on the free ion activity in solution (such as BLM or FIAM models) are applicable to metal uptake by microorganisms in a real natural medium.

Raman spectroscopy was used for obtaining the individual N,N-dimethylformamide (DMF) and protic N-methylformamide (NMF) solvation numbers of manganese (II), nickel (II) and zinc (II) ions. The metal ions were preferentially solvated by DMF at xDMF > 0.5 whereas no preferential solvation occurred in mixtures with DMF mole fraction of xDMF < 0.5.

Experimental data are presented showing that, for a light heavy ion such as Carbon, large collection-efficiency losses appear in Silicon Surface Barrier detectors for large enough ion fluences. This effect, apparently related to the onset of radiation damage of the detector, shows an S-shape behavior with the fluence above threshold. Index Terms--Ion fluence, pulse height defect, Rutherford backscattering, silicon detector.

Selective bond formation with the series of first-period transition metal ions is accomplished using the metalloligand L(super Cu) [Cu(2,4-pydca)(sub 2)](super 2-). New Cu(super II) metalloligand [Cu(2,4-pydca)(sub 2)](super 2-) L(super Cu) controlled bond formation for the first-period transition metal ions and magnetic properties.

A copper compound structure with peptide Gly-Trp belongs to the P212121 space group with Z=4. These magnitudes are studied on the basis of structural information about intervening long chemical paths.

Ab initio, molecular orbital methods are used to study the geometric structures and stability of Na (super +) Arn clusters. The clusters of n = 6, 8, and 10 have a high symmetry of Oh, D4d, and D4d respectively. The clusters of n = 3 and 4 are deformed from the expected high symmetric configuration.

Periodic ab initio QM calculations are employed in order to study structure and redox properties of Cr, Mn, Fe, and Co trivalent transition metal dopants in A1POs-34. The results show that the local environment of Mn and Co dopants is a distorted tetrahedron due to the Jahn-Teller distortions.

Periodic ab initio QM calculations are applied to study the structure and acidity of Mg, Ca, Cr, Mn, Fe, Co, Ni, Zn, and Sr divalent metal ions in the A1PO-34 framework, charge compensated by an acid proton on a neighboring oxygen. The results show that the local environment of the divalent dopants is a distorted tetrahedron, in which the Me-O(sub H) bond of the dopant to the protonated oxygen is ~0.15 degree angstron longer than the other three Me-O bonds.

Threshold collision-induced dissociation of M(super +1) (adenine) with xenon is studied using guided ion beam mass spectrometry. Theoretical calculations on Cu(super +) indicate distinct differences in the binding site propensities of adenine to the alkali vs transition metal ions, a consequence of s-d sigma hybridization on the latter.

A study on the metal ion binding characteristics of recombinant Plasmodium falciparum M17 leucine aminopeptidase (rPfLAP) is carried out to gain insight into the two metal-binding active sites, a readily exchangeable site (site 1) and a tight binding site (site 2). The type of metal ion present at site 1 is observed to affect not only the catalytic efficiency of the enzyme for peptide substrates but also the mode of binding by bestatin, a metal-chelating inhibitor of M17 aminopeptidases with antimalarial activity.

Electron transfer has occurred from the TTF units to the substituted quinone unit in a new TTF-quinone-TTF triad containing the N,N-dialkylaniline-substituted quinone unit flanked by two TTF units, in the presence of metal ions ([Pb.sup.2+], [Zn.sup.2+], and [Sc.sup.3+]). The metal ion-promoted electron transfer and the intramolecular charge transfer are tuned by alternating ultraviolet and visible light irradiation in the presence of spiropyran.

The synthesis and metal cation complexation and inter-relation between interfacial properties of two new crown ether ionophores are discussed. The results obtained offer insight into the differentiation in the membrane-related, complexation properties and conformational changes in the two crown ether derivatives.

The article reports the stability of coacervate core micelles formed between charged-neutral diblock copolymers and oppositely charged coordination polymers formed from metal ions and bisligand molecules. The density of the micelles containing metal coordination polymers decreases with increasing ionic strength.

The synthesis and studies of wetting properties of cross-linked imidazolium-based [poly([ViEtIm.sup.+][Br.sup.-])] microparticles are demonstrated. The interaction between anions and the microparticles facilitated reversible exchange of halogenides and also modified the polymer network elasticity as ion concentration increased to achieve softer network.

The surfactant-directed assembly of mesoporous metal/germanium-based semiconducting materials from coupling of anionic [([Ge.sub.9]).sup.4-] clusters with various linking metal ions is described. The photoemission intensity in the mesoporous intermetallic germanium-based frameworks is selectively suppressed by adsorbing electron-acceptor species such as tetracyanoethylene molecules, but has remained unchanged when exposed to electron-donor species such as tetrathiafulvalene molecules.

The density functional theories were used to determine the effects on metal ions [Li.sup.+], [Na.sup.+], [K.sup.+], [Mg.sup.2+], [Ca.sup.2+], [Ni.sup.2+], [Cu.sup.2+], and [Zn.sup.2+] and water on structures of Arg.M[([H.sub.2]O).sub.m], m = 0, 1 complexes. The relative stability of individual complexes were found to be affected by even one molecule and water, the metallic complexes of the neutral L-arginine were the most stable species and [Cu.sup.2+] cation exhibited the strongest affinity to arginine.

The article reports systematic studies of the self-assembly of Zn(II) and Cd(II) ions with a bis-bidentate ligand 3,5-bis(benzimidazol-2-yl)pyrazole ([H.sub.3]L). The results obtained provide insights into the pentanuclear complexes with different stability in the solution that depends on the metal ions and the counteranions.

The [super 1]H relaxation behavior of an organic molecule that is adsorbed in a zeolite exchanged with transition metal ions is studied. The influence of the exchange of adsorbate molecules is described and the occurrence of rapid exchange has led to an increasing of the spin-spin relaxation time and hence a narrowing of the resonance line.

A simple lanthanide tag and strategy is described for immobilization of a lanthanide close of the protein by using a single cysteine residue. The 4MMDPA tag has offered many advantages, including its small size and reduced likelihood of interference in studies of intermolecular interactions and its formation of stable nonchiral 1:1 complexes with metal ions.

The reactions of coinage metal catalysts where a heterocyclic ring is generated are discussed. The catalysis of coinage metals has generated a heterocyclic ring and they have also catalyzed the side ring closure of heteroycles.

A conformational selective synthesis, the X-ray crystal structures and the binding properties of N-benzylhexahomotriaza-p-chlorocalix[3]trinaphthylamide are described. The analyses of the complexes have shown that recognition is affected by [Cd.sup.2+], [Pb.sup.2+] and [F.sup.-] ions.

The synthesis of several different one-size adjustable-gap quaternary cluster anions by the reactions of defined mixtures of ternary salts and transition-metal ions is discussed. The approach has shown to be extremely useful for controlling the electron excitation energies of the water-soluble chalcogenidometalate compounds.

The first example of metal ion catalyzed phosphate diester complexes which promote isomerization and cleavage close to neutral pH is reported. The rate enhancement for isomerization and cleavage observed from the combination of the Lewis acid effect of the Zn ions and hydrogen bond donors of the ligand stabilizes the anionic oxygens of the phosphorane.

The first example of photoluminescence emission from the electronically excited states of the plutonyl ion is reported. The results from analysis of excited-state lifetime reveal multiple relaxation pathways in the electronic structure of Pu[O.sub.2][Cl.sub.4.sup.2-].

The density functional theory calculations were performed to understand the [4.sup.C.sub.1], [1.sup.C.sub.4] and [2.sup.S.sub.O] ring conformation of methyl [beta]-D-xylopyranoside (1) with divalent metal cations, M = [Mg.su.2+], [Ca.sup.2+], [Zn.sup.2+], and [Cd.sup.2+]. The formation of most stable structure of bridging complexes [[M[([H.sub.2]O).sub.4]1].sup.2+] was found to result from coordination of the metal to O3 and O4 of methyl [beta]-D-xylopyranoside in its [4.sub.C.1] ring conformation.

A density functional theory is developed for rodlike ions sandwiched between two like-charged planar surfaces. The results have highlighted the importance of the rodlike internal structure that condensing agents like polyamines, peptides or polymer segments have displayed.

The reactions of 3-[(2-amino-ethyl)sulfanyl]-4,6-di-tert-butylbenzene-1,2-diol (Cydo) with [Zn.sup.II], [Ni.sup.II] and [Fe.sup.III] are examined. The counterion is less important as neither zinc(II) sulfate nor zinc(II) chloride have promoted the transformation.

The effect of the choice of electrolyte on the separability of different metal ions by pyroprocessing is examined. The studies have shown that the activity coefficients have varied systematically with cation size for a set of trivalent cations.

Several studies are conducted for the computation of the metal-coupled folding of the [Cys.sub.2][His.sub.2] zinc-finger motif. The zinc ion is found to play a very important role in the stabilizing and folding of the native structure.

Optically switchable chelates are designed by introducing an iminodiacetate group into photochromic nitrobenzospiropyran with structurally different spiro(SP) and merocyanine(MC) states. The ability of the fluorescent MC state to bind to metal ions is useful in studies that require control of metal ions within living cells.

The molecular mechanism of the metal-induced A[beta] oligomerization is investigated with extensive metal ion titration NMR experiments. The transition-metal ions selectively affect the N-terminal region and facilitate intermolecular interactions between the hydrophobic residues.

The structural, as well as the energetic characteristics of the various cation-[pi] interactions of various bare and coordinatively saturated metal ions are studied. The results show that an increase in the number of water molecules leads to an increase in the distance between the cation and the [pi]-system.

The biochemical, structural, and biophysical characterization of GloB, the glyoxalase II (GLX2) enzyme from the pathogen Salmonella typhimurium is reported. The findings suggest that the iron uptake in glyoxalates II could be attributed to the presenece of a conserved Asp residue acting as a second-shell ligand.

A combination protein is designed, which has included the de novo designed metal-ion-responsive trimeric coiled-coil and the circularly permutated green fluorescent protein (cpGFP). The fluorescence emission is detected when the combination protein is expressed in Escherichia coli, thus indicating that the protein is useful in monitoring transition metal ions.

The effects of metal ion binding on structural dynamics of human hemopexin (HX) were investigated by monitoring metal-ion linked changes in the structure of protein as reflected by near UV CD spectrum and the UV absorption spectrum. The binding affects the heme-scavenging activity of the protein through the alteration of protein structure.

The pre-steady state human ferrochelatase (R115L) has displayed a stoichiometric burst of product formation and substrate consumption, which is consistent with a rate-determining step following metal ion chelation. Both steady state and pre-state methods are required for the evaluation of structure-function data for site-directed mutants.

The study describes the rational design of near-IR (NIR) luminescent lanthanide redox reporters, which can then help in transposing a visible fluorescent switch to longer wavelengths. These switches add a luminescent lanthanide complex to a small fluorogenic substrate, hence demonstrating the importance of the method in preserving enzyme substrate fidelity.

A DNA is designed and synthesized that can undergo a reversible structural transition between a compact antiparallel G-quadruplex and a long guanine nanowire (G-wire), depending on external signals. The results have shown that a DNA oligonucleotide incorporating the 2,2'-bipyridine unit has acted as a G-wire switch that can be controlled by chemical input signals like divalent metal ions.

Extensively hydrated divalent alkaline earth metal ions are applied as chemical thermometers to investigate the internal energy deposition that happen in collisions between ions and thermally generated free electrons (ECD). It is demonstrated that ions in an ECD simulation are not activated by elastic non-capture collisions with electrons when low electron kinetic energies are applied.

The molecular and ionized ions in the inner plasma core are studied to demonstrate the multibubble sonoluminescence (MBSL) and single-bubble sonoluminescence (SBSL) of sulfuric acid at various conditions. The presence of Ar emission in the process proves the presence of an optically opaque plasma core, as strong Ar lines are present only at low acoustic intensities and are lost with increasing acoustic intensity.

The contributions of the protonated C41 base triple to the metal ion- and pH-dependence of the reaction are investigated. The results have shown that a protonated base triple allows the wild-type ribozyme to maintain the activity at acidic pH, which plays a vital role in the life cycle of the virus.