the complexation reactions between mg2+, ca2+, sr2+ and ba2+ metal cations with 15-crown-5 (15c5) were studied in acetonitrile (an)-methanol (meoh) binary mixtures at different temperatures using conductometric method. 15c54 forms 1:1 complexes with mg2+, ca2+ and sr2+ cations in solutions. the ma2+ cation forms a 2:1 complex (ratio of lighand to cation) in solutions. a linear relation was obse...

Induction of outer membrane protein H1 in Pseudomonas aeruginosa results in decreased susceptibility to aminoglycosides, polymyxin B, and EDTA. We have previously shown that protein H1 can become the major cellular protein in cells grown in low (0.02 mM) Mg2+. The induction of protein H1 was prevented by supplementation of low Mg2+ medium with Mg2+, Ca2+, Mn2+, or Sr2+ (each at 0.5 mM), but not...

The effect of divalent cations on cation fluxes across the chloroplast envelope and on photo­ synthetic reactions of intact spinach chloroplasts was investigated. In the absence of EDTA, divalent cations inhibited photosynthetic C02-fixation and PGAreduction at low PGA concentrations, but had almost no effect on the reduction of OAA, BQ, and on PGA-reduction at high PGA concentrations. The inhi...

HutP is an RNA-binding protein that regulates the expression of the histidine utilization (hut) operon in Bacillus subtilis, by binding to cis-acting regulatory sequences on hut mRNA. It requires L-histidine and an Mg2+ ion for binding to the specific sequence within the hut mRNA. In the present study, we show that several divalent cations can mediate the HutP-RNA interactions. The best divalen...

We describe the qualitative and quantitative analysis of the complexation properties towards cations of a cyclic peptoid hexamer composed of alternating α- and β-peptoid monomers, which bear exclusively chiral (S)-phenylethyl side chains (spe) that have no noticeable chelating properties. The binding of a series of monovalent and divalent cations was assessed by 1H NMR, circular dichroism, fluo...

For cell division, negatively charged chromatin, in which nucleosome fibers (10 nm fibers) are irregularly folded [1-5], must be condensed into chromosomes and segregated. While condensin and other proteins are critical for organizing chromatin into the appropriate chromosome shape [6-17], free divalent cations such as Mg2+ and Ca2+, which condense chromatin or chromosomes in vitro [18-28], hav...

The conduction properties of the alkaline earth divalent cations were determined in the purified sheep cardiac sarcoplasmic reticulum ryanodine receptor channel after reconstitution into planar phospholipid bilayers. Under bi-ionic conditions there was little difference in permeability among Ba2+, Ca2+, Sr2+, and Mg2+. However, there was a significant difference between the divalent cations and...

Biological membrane fusion employs divalent cations as protein cofactors or as signaling ligands. For example, Mg2+ is a cofactor for the N-ethylmaleimide-sensitive factor (NSF) ATPase, and the Ca2+ signal from neuronal membrane depolarization is required for synaptotagmin activation. Divalent cations also regulate liposome fusion, but the role of such ion interactions with lipid bilayers in Ra...

The kidney plays an important role in maintaining the systemic Ca2+ and Mg2+ balance. Thus the renal reabsorptive capacity of these cations can be amended to adapt to disturbances in plasma Ca2+ and Mg2+ concentrations. The reabsorption of Ca2+ and Mg2+ is driven by transport of other electrolytes, sometimes through selective channels and often supported by hormonal stimuli. It is, therefore, n...

Viscosity, electrical conductivity and deposit weight were determined for Electrophoretic deposition (EPD) Mg2+-, Y3+-, La3+- and Ce4+-doped alumina's ethanolic suspensions prepared at dopant concentration between 350 to 1350 ppm. The concentration of XCly (X, y were: Mg, 2; Y, 3; Ce, 3 and La, 3, respectively) the charging salt, is also found to be a critical factor to control the viscosity. I...