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[Effect of salt supplements on lipid growth and synthesis by yeast cultivated on peat oxidates].

The accumulation of biomass and lipids and their fatty acid composition were investigated during cultivation of the yeast Candida tropicalis and Lipomyces lipoferus on peat oxidates supplemented with inorganic compounds containing nitrogen, phosphorus, potassium and magnesium. The absence of additional sources of the above elements from the nutrient substrate inhibited the culture growth. In order to optimize cultivation of lipid synthesizing yeast on peat oxidates, the above compounds should be added in certain concentrations.

Ascomycota↗
PubMed1999

Formation of Separated versus Contact Ion Triplets in Magnesium Thiolates. Synthesis and Characterization of [Mg(15-crown-5)(SCPh(3))(2)] and [Mg(15-crown-5)(THF)(2)][S-2,4,6-tBu(3)C(6)H(2))](2).

The synthesis and structural characterization of two magnesium thiolate complexes are described. Both compounds were prepared by analogous reactions routes, namely, alkane elimination and transamination, but using differently sized ligands. Utilization of the smaller HSCPh(3), resulted in the formation of [Mg(15-crown-5)(SCPh(3))(2)], 1, displaying a seven-coordinate magnesium center with two magnesium-sulfur bonds. Employment of the sterically more encumbered HS-2,4,6-tBu(3)C(6)H(2) yielded a separated cation and anions as displayed in [Mg(15-crown-5)(THF)(2)][S-2,4,6-tBu(3)C(6)H(2)](2), 2. Compound 2 exhibits a seven-coordinate cation, completing its coordination environment with five metal-crown-ether interactions in addition to two tetrahydrofuran (THF) contacts. The compounds were characterized by IR and NMR spectroscopy in addition to X-ray crystallography. Crystal data with Mo Kalpha (lambda = 0.710 73 Å) are as follows: 1, C(48)H(50)MgO(5)S(2), a = 8.4785(4) Å, b = 9.3595(5) Å, c = 13.8306(6) Å, alpha = 87.332(1) degrees, beta = 85.929(1) degrees, gamma = 68.733(1) degrees, Z = 1, triclinic; 2, C(54)H(94)MgO(7)S(2), a = 13.6755(2) Å, b = 12.8045(6) Å, c = 32.7127(12) Å, beta = 97.87(1) degrees, Z = 4, monoclinic.

Journal Article↗
PubMed2000

[A 90-day repeated dose oral toxicity study of magnesium chloride in F344 rats].

In order to examine the toxicity of magnesium chloride hexahydrate, four groups of 10 male and 10 female F344 rats received the compound by dietary supplementation at 2.5, 0.5, 0.1 or 0% for 90 days. No treatment-related death was observed during the study. Transient soft stool and sustained increase in water consumption were observed both in males and females of the 2.5% group and slight reduction in body weight gain was noted in the high-dose males. There were no toxic changes in food consumption, organ weights, hematology and biochemistry, and histopathological examinations in any treated-groups. Based on these results, the no-observed-adverse-effect-level was estimated to be 0.5%, and 2.5% is considered to be appropriate as highest dose for a 2-year carcinogenicity study.

Administration, Oral↗
PubMed1975

Prenyltransferase from Saccharomyces cerevisiae. Purification to homogeneity and molecular properties.

Prenyltransferase (EC 2.5.1.1) has been purified to homogeneity from the supernatant fraction of yeast by ammonium sulfate fractionation, diethylaminoethyl-cellulose and hydroxylapatite chromatography, and column isoelectric focusing techniques. The active enzyme from isoelectric focusing columns emerged as a single symmetrical peak with specific activities 15- to 35-fold higher than previously reported preparations. The enzyme was found to be homogeneous by continuous polyacrylamide gel electrophoresis at pH 8.4 and discontinuous polyacrylamide gel electrophoresis at pH 6.9 as well as sodium dodecyl sulfate polyacrylamide electrophoresis at pH 7.0. By means of gel chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis, the protein was shown to be a dimer with a molecular weight of 84,000 plus or minus 10%. The isoelectric point of the enzyme was determined to be 5.3. The enzyme synthesizes farnesyl and geranylgeranyl pyrophosphates from dimethylallyl, geranyl, and farnesyl pyrophosphates. Michaelis constants for the enzyme were 4, 8, and 14 mu M for isopentenyl, dimethylallyl, and geranyl pyrophosphates, respectively.

Alkenes↗
PubMed1986

On vasodilators, magnesium and second messengers.

Detailed hemodynamic studies of vasodilating compounds in anesthetized dogs were performed. Multichannel electromagnetic flowmetry at organ level showed for a number of peptide hormones and biogenic amines that each chemical entity had its own "map" of vascular responses. In contrast magnesium-ions appear to reduce vascular resistance in each vascular area, in a similar time-frame, similar dose-dependency and without changing left ventricular volume output or perfusion of any vascular bed. The restricted vascular activity of the hormones and amines is set against the homogeneity of the morphology of arteriolar walls throughout the body. The hypothesis is put forward that these compounds cause vasodilation through release of one or more metabolites from their target cells. Such a metabolite would then act as a second messenger. A number of requirements are set forth for reactions to be expected after intravenous administration of such a hypothetical metabolite. It is concluded that magnesium and may be potassium fulfill these requirements, and should therefore be considered as potential second messenger vasodilators.

Animals↗
PubMed1992

Interaction between polyethylene films and bromhexine HCl in solid dosage form. IV. Prevention of the sorption by addition of magnesium aluminum silicate.

The effects of magnesium aluminum silicate (MAS) addition on the sorption of bromhexine HCl to polyethylene film in tablets were studied. The addition of MAS prevented the sorption of bromhexine HCl to polyethylene film. In order to investigate the mechanism, the interaction between bromhexine HCl and MAS was studied by the powder X-ray diffraction method. It was observed that bromhexine HCl was preferentially adsorbed to the surface of MAS rather than to polyethylene film. The adsorption was accelerated at high temperature and reduced pressure conditions. The sorption of bromhexine base and bromhexine HCl to packaging material were compared using tablet dosage forms. The sorption of bromhexine base to polyethylene film was greater than that of bromhexine HCl.

Aluminum Compounds↗
PubMed1999

In vitro effect of Cl2Ca and Cl2Mg on warfarin-human serum albumin (HSA) binding.

The binding of warfarin to 10 mumol/L human serum albumin (HSA) was studied in vitro by equilibrium dialysis in presence of two different calcium concentrations. At 2.3 and 23 mmol/L calcium concentrations, the percentage binding decreased. The number of saturable sites of warfarin-HSA at these two calcium concentrations were 1.02 and 1.23 respectively; the number of saturables sites observed with warfarin alone was higher (n1 = 1.32). The association constant for saturable sites (K1 = 0.187 mumol-1) and the affinity coefficient for the nonsaturable sites (n2K2 = 0.0955) remained unchanged. The binding to HSA was 98 per cent at therapeutic levels, that is a physiological concentrations of protein and therapeutic levels of warfarin, in the presence of several concentrations of calcium (2.5; 5; 25; 50 and 100 mmol/L) or magnesium (1;2;10;50 and 100 mmol/L) as chloride compounds, the free fraction of warfarin remained constant until calcium or magnesium reached concentrations of 50 mmol/L, in which cases the percentage binding fell to 92 per cent. In conclusion a displacement of bound warfarin can be expected only if the plasma concentrations of calcium or magnesium and as well chloride concentration are raised by much.

Calcium Chloride↗
PubMed1989

A kinetic study of the effects of phosphate and organic phosphates on the activity of phosphoenolpyruvate carboxylase from Crassula argentea.

The effects of phosphate and several phosphate-containing compounds on the activity of purified phosphoenolpyruvate carboxylase (PEPC) from the crassulacean acid metabolism plant, Crassula argentea, were investigated. When assayed at subsaturating phosphoenolpyruvate (PEP) concentrations, low concentrations of most of the compounds tested were found to stimulate PEPC activity. This activation, variable in extent, was found in all cases to be competitive with glucose 6-phosphate (Glc-6-P) stimulation, suggesting that these effectors bind to the Glc-6-P site. At higher concentrations, depending upon the effector molecule studied, deactivation, inhibition, or no response was observed. More detailed studies were performed with Glc-6-P, AMP, phosphoglycolate, and phosphate. AMP had previously been shown to be a specific ligand for the Glc-6-P site. The main effect of Glc-6-P and AMP on the kinetic parameters was to decrease the apparent Km and increase Vmax/Km. AMP also caused a decrease in the Vmax of the reaction. In contrast, phosphoglycolate acted essentially as a competitive inhibitor increasing the apparent Km for PEP and decreasing Vmax/Km. Inorganic phosphate had a biphasic effect on the kinetic parameters, resulting in a transient decrease in Km followed by an increase of the apparent Km for PEP with increasing concentration of phosphate. The Vmax also was decreased with increasing phosphate concentrations. Further, the enzyme appeared to respond to the complex of phosphate with magnesium. In the presence of a saturating concentration of AMP, no activation but rather inhibition was observed with increasing phosphate concentration. This is consistent with the binding of phosphate to two separate sites--the Glc-6-P activation site and an inhibitory site, a phenomenon that may be occurring with other phosphate containing compounds. High concentrations of phosphate with magnesium were found to protect enzyme activity when PEPC, previously shown to contain an essential arginine at the active site, was incubated with the specific arginyl reagent 2,3-butanedione, consistent with the binding of phosphate at the active site. Data were successfully fitted to a rapid equilibrium model allowing for binding of the phosphate-magnesium complex to both the activation site and the active site which accounts for the activation/deactivation observed at low substrate concentrations. Effects on the Vmax of the reaction are also addressed. Factors controlling the differential affinity of various effectors to the active site or activation site appear to include charge distribution, size, and other steric factors.

Adenosine Monophosphate↗
PubMed2006

Catalytic mechanism of transition-metal compounds on Mg hydrogen sorption reaction.

The catalytic mechanisms of transition-metal compounds during the hydrogen sorption reaction of magnesium-based hydrides were investigated through relevant experiments. Catalytic activity was found to be influenced by four distinct physico-thermodynamic properties of the transition-metal compound: a high number of structural defects, a low stability of the compound, which however has to be high enough to avoid complete reduction of the transition metal under operating conditions, a high valence state of the transition-metal ion within the compound, and a high affinity of the transition-metal ion to hydrogen. On the basis of these results, further optimization of the selection of catalysts for improving sorption properties of magnesium-based hydrides is possible. In addition, utilization of transition-metal compounds as catalysts for other hydrogen storage materials is considered.

Journal Article↗
PubMed1980

The granulation of ternary mixtures: the effect of the solubility of the excipients.

The importance of excipient solubility in wet granulation has been shown using mixtures of lactose and boric acid containing third components of differing solubility characteristics. Sucrose dissolved in the binder solution and increased the amount of liquid available to form liquid bridges between other solid particles and therefore increased the number of solid bridges when the damp mass was dried. Thus, stronger, larger granules were formed. The results obtained with Sta-Rx 1500 and magnesium carbonate powders were also dependent upon the extent of solubility of these powders in the granulating solution.

Boric Acids↗