Calcium clusters

Detailed examination of another madder preparation proved that the sample can be premordanted with alum. [ 19] After hydrolysis performed with hydrochloric acid and extraction with M-amyl alcohol, only four colourants are found alizarin, purpurin, and probably lucidin and ruberythric acid. Additionally, signals at m/z 525 and 539 are observed in the mass spectrum. Analysis of the preparation by inductively coupled plasma mass spectrometry (ICP MS) shows that aluminium and calcium are the main inorganic components of the sample. This is why it was suggested that the signal at m/z 539 can be attributed to the complex of aluminium with alizarin, and the second one, observed at m/z 525, to an aluminium-calcium cluster. 

The NCI domain of type VIII collagen is important for trimerization. ACRP30/adiponectin, a member of the complement Clq family of proteins,and the type X collagen NCI domain have similar structures as the NCI domain of type VIII collagen however, the type Vlll collagen NCI trimer lacks the buried calcium cluster found in the type X collagen NCI trimer. The crystal structure of this domain has similarity to the TNF (tumor necrosis factor) family of proteins (PDB accession number 1091). ... 

Nonrepetitive but well-defined structures of this type form many important features of enzyme active sites. In some cases, a particular arrangement of coil structure providing a specific type of functional site recurs in several functionally related proteins. The peptide loop that binds iron-sulfur clusters in both ferredoxin and high potential iron protein is one example. Another is the central loop portion of the E—F hand structure that binds a calcium ion in several calcium-binding proteins, including calmodulin, carp parvalbumin, troponin C, and the intestinal calcium-binding protein. This loop, shown in Figure 6.26, connects two short a-helices. The calcium ion nestles into the pocket formed by this structure. 

Ca2+ sensing receptor, a member of G-protein coupled receptors, is composed of seven transmembrane spanning domains. The extracellular domain contains clusters of negatively charged amino acids sensing even small fluctuations of extracellular calcium. Mutations in this receptor cause inheritable hypo- and hypercalcemic syndromes. 

Sodium carboxymethyl chitin and phosphoryl chitin had most evident influences on the crystallization of calcium phosphate from supersaturated solutions. They potently inhibited the growth of hydroxyapatite and retarded the rate of spontaneous calcium phosphate precipitation. These chitin derivatives were incorporated into the precipitate and influenced both the phase and morphology of the calcium phosphate formed (flaky precipitate resembling octacalcium phosphate instead of spherical clusters in the absence of polysaccharide) [175]. 

Isolated polynucleotide clusters from Rhodococcus opacus which encode four polypeptides possessing the activities of a NHase (a and /3 subunits), an auxiliary protein P15K that activates the NHase, and a cobalt transporter protein were expressed in Escherichia coli DSM 14459 cells [34]. Methionine nitrile was added continuously to a suspension of the transformant cells (5.6% w/v of wet cells) in phosphate buffer (50 mM, pH 7.5) at 20 °C, at a rate where the nitrile concentration did not exceed 15 g L 1 while maintaining the pH constant at 7.5. After 320 min, the nitrile was completely converted into amide, corresponding to a final product concentration of 176 gL1.4-Methylthio-a-hydroxybutyramide is readily hydrolyzed with calcium hydroxide, where the calcium salt of 4-methylthio-a-hydroxybutyric acid (MHA) can be directly used as a nutritional supplement in animal feed as an alternative to methionine or MHA. 

We present here the results of abundance measurements of iron, calcium and nickel in four open clusters, from UVES spectra of solar type stars. A code developed by one of the authors (Francois) performs line recognization, equivalent width measurements and finally obtains the abundances by means of OSMARCS LTE model atmosphere [4]. Temperature, gravity and microturbulence velocity have to be input to the program. This is made in an automatic way for a grid of values chosen on photometric basis. Those that best reproduce excitation and ionization equilibria are selected and used, namely when no significant trend of the computed abundances is seen, neither versus the excitation potential of the line nor versus its equivalent width, and for which the abundances obtained with lines of different ionization stages of the same specie give equal results within the errors. This check is made with iron lines, we have in fact at least thirty Fe I lines in each star, and six Fell lines. 

General Methods. Methanol used in kinetic runs was distilled from sodium methoxide or calcium hydride in a nitrogen atmosphere before use. Freshly distilled cyclohexanol was added to the methanol in the ratio 6.0 ml cyclohexanol/200 ml MeOH and was used as an internal standard for gas chromatographic (GC) analysis. Benzaldehyde was distilled under vacuum and stored under nitrogen at 5°. Other aldehydes (purchased from Aldrich) were also distilled before use. The corresponding alcohols (purchased from Aldrich) were distilled and used to prepare GC standards. All metal carbonyl cluster complexes were purchased from Strem Chemical Company and used as received. Tetrahydrofuran (THF) was distilled from sodium benzophenone under nitrogen before use. 

The first Ca/Sn-mixed phosphandiide cluster 43 has been prepared by reaction of the calcium phosphanide 44 with Sn[N(SiMe3)2]2 in THF... 

In an extension to the studies mentioned above, the actions of 11 commercial pyrethroids on calcium influx and glutamate release were assessed using a high-throughput approach with rat brain synaptosomes [75, 76]. Concentration-dependent response curves for each commercial pyrethroid were determined and the data used in a cluster analysis. Previously characterized Type II pyrethroids that induce the CS-syndrome symptoms (cypermethrin, deltamethrin, and esfenvalerate) increased calcium influx and glutamate release, and clustered with two other ot-cyano pyrethroids (p-cyfluthrin and A-cyhalothrin) that shared these same actions. Previously characterized Type I pyrethroids (bioallethrin, cismethrin, and fenpropathrin) did not share these actions and clustered with two other non-cyano pyrethroids (tefluthrin and bifenthrin) that likewise did not elicit these actions. 

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