(1) Some mechanisms that can provide catalysis of phosphoryl transfer through a metaphosphate-like transition state are reviewed briefly.
(2) Both at the substrate level and at the membrane level, orthophosphate energization to metaphosphate, by removal of an oxide anion (O2-), brings about a decrease in pKa with the concomitant dissociation of the two protons (2 H+), whereas de-energization of metaphosphate to orthophosphate, by addition of an oxide anion, brings about an increase in pKa with the concomitant fixation of two protons.
(3) As part of a comprehensive effort to evaluate the toxicological potential of calcium sodium metaphosphate fiber (Phosphate Fiber), the in vitro cytotoxicity of the fiber in cultured cells was studied.
(4) A metaphosphate intermediate appears to be involved.
(5) Calcium metaphosphates (CMP's)--a unique class of phosphate minerals possessing polymeric structures, [Ca(PO3)2]n, and having refractive indices of approximately 1.54-1.59-- are optically compatible with resins such as BIS-GMA.
(6) The fibers were rock wool [average diameter (D) = 6.1 microns, average length (L) = 296 microns], fiberglass (D = 0.65 microns, L = 16.8 microns), potassium titanate fiber (D = 0.36 microns, L = 7.17 microns), calcium sulfate fiber (D = 1.0 microns, L = 17.8 microns), basic magnesium sulfate fiber (D = 0.45 microns, L = 22.4 microns), and metaphosphate fiber (D = 2.38 microns, L = 64.1 microns).
(7) The results indicated that one of the two test dentifrices, containing 0.3% triclosan, 2% of a copolymer, and 0.76% sodium monofluorophosphate in an insoluble sodium metaphosphate abrasive system, significantly reduced plaque formation by 16% when compared to the placebo dentifrice.
(8) Detailed analysis of appropriate 31P nuclear-magnetic-resonance spectra shows that under the usual laboratory conditions, carbodiimide-induced condensation of orthophosphoric acid in a number of solvents leads to condensation only slightly beyond the metaphosphate composition in the presence of strong tertiary amines; whereas in the absence of amine, the condensation proceeds into the ultraphosphate region about halfway between the metaphosphate and phosphoric anhydride compositions.
(9) With arylsulphonyl chloride as condensing reagent monomeric nucleotide derivative B (nucleoside metaphosphate or its pyridinium adduct) is the highly reactive intermediate.
(10) The occurrence of linear condensed polyphosphates and cyclic condensed metaphosphates was studied by means of pulse-labeling with 32P-orthophosphate (3--5h) in a number of Phaeophyceae species: Pylaiella litoralis, Ilea fascia, Ectocarpus siliculosus and also Rhodophyceae species: Ceramiumdeslongchampsii, C. rubrum, Rhodomela confervoides, Porphyridium purpureum and P. aerugineum.
(11) In an experiment to ascertain the degradability of calcium sodium metaphosphate (CSM) fiber in vitro, 32P-labeled CSM fiber was incubated in media with or without rat lung epithelial cells (LEC) or rat alveolar macrophages (RAM).
(12) It is therefore suggested that, for the enzymatically catalyzed hydrolysis of phosphate compounds going via the formation of a metaphosphate intermediate, the role of any arginine residues at the active site is primarily one of binding and positioning the substrate.
(13) Electronic energy--resulting either from electron excitation or localization--is the obligatory link between the different forms of energy (light, redox, acid-base, metaphosphate-orthophosphate) transducible by biochemical systems.
(14) Phosphates with multiple negative charges can react by way of the monomeric metaphosphate ion PO3- as an intermediate.
(15) Concentrative absorption of inorganic phosphate observed in the stripped and everted intestine of the carp disappeared, when Na concentration of the Ringer solution was reduced from 150 to 7 mM, or when orthophosphate was replaced with metaphosphate.
(16) In this study we examined the shearing adhesive strength between a calcium metaphosphate glass-ceramic (CMP) and various luting materials.
(17) Three basic energy-transducing systems in bioenergetics, namely, redox, acid-base and metaphosphate-orthophosphate, couple between them through the acylium cation (Equation: see text)-carboxylate-anion (R-COO-) pair.
(18) For ketimines having carboxylate or phosphonate groups substituted on the beta-carbon atoms of the keto acid residue, there is a hydrogen ion or metal ion-activated covalent bond pathway which involves a shift of electron pairs toward the coordinated ketimine nitrogen, leading to beta-gamma, C-C or C-P bond fission and release of carbon dioxide or metaphosphate, respectively.
(19) Two-dimensional cellulose thin layer chromatography revealed that in all species studied 32P-radioactivity was generally present in all oligopolyphosphates containing 2 to 7 phosphate residues, in cyclic metaphosphates (tri-, tetra-, penta- and hexametaphosphates) and in high-molecular-weight condensed phosphates which remained at the starting point.
(20) The fact that the "metaphosphate" (delta-5.1) first becomes detectable only at later stage of the activation and does coexist with pyrophosphate and triphosphate suggests that the pyridinium derivative of "metaphosphate" is most probably not directly formed from the hypothetical mixed anhydride or active "pseudourea" right at the beginning of the reaction of pdTac with TPS or DCC, but rather formed at later stage of the activation reaction from the degradation of the pyro- and triphosphates by the activating agent.
Phosphate
Definition:
(n.) A salt of phosphoric acid.
Example Sentences:
(1) The proportion of motile spermatozoa decreased with time at the same rate when samples were prepared in either HEPES or phosphate buffers.
(2) One hour after direct mechanical cardiomassage (DMCM) a moderately pronounced edema of the intercellular spaces in the basal compartment of the seminiferous epithelium, normal content of lactate and succinate dehydrogenases, and a certain decrease in the activity of glucose-6-phosphate dehydrogenases and NAD- and NADP-diaphorases were noted.
(3) Changes in cardiac adenosine triphosphate (ATP), phosphocreatine (PCr) and inorganic phosphate (Pi) were followed and intracellular pH (pHi) was estimated from the chemical shift of Pi.
(4) Plasma membranes were isolated from rat kidney and their transport properties for sodium, calcium, protons, phosphate, glucose, lactate, and phenylalanine were investigated.
(5) The 0.1 M phosphate buffer eluant was electrophoretically heterogeneous and did not elicit the production of bactericidal antibodies in rabbits.
(6) The acute effect of alcohol manifested itself by decreasing mitochondrial respiration, compensated by increased glycolytic activity of the myocardium so that myocardial energy phosphate concentration remained unchanged.
(7) A retrospective study was done in 86 patients on dialysis in order to evaluate the doses of aluminum hydroxide (OH3 Al) received to achieve a better serum phosphate control.
(8) Infusion of 1 unit of 25-HCC per hour for 6 hours induced an antiphosphaturia only when administered with 0.2 units of PTH per hour, while neither agent alone changed phosphate excretion.
(9) The present results using approximately 12% hemoglobin concentration in 0.1 M Bistris buffer at pD 7 and 27 degrees C with and without organic phosphate show that there is no significant line broadening on oxygenation (from 0 to 50% saturation) to affect the determination of the intensities or areas of these resonances.
(10) The amount of phosphate incorporated per molecule was higher for NF 200 than for NF 145 and NF 68.
(11) Resorption of calcium and depositon of inorganic phosphates in the implanted ceramics suggested that ions were being exchanged with the body fluids.
(12) sn-Glycerol 3-phosphate was found to decrease the quasi-stationary concentration of Fru 2,6-P2.
(13) At constant arterial pO2, changes in coronary flow were associated with changes in energy-rich phosphates, but not systematically with changes in coronary venous pO2.
(14) Antigenic specificity was demonstrated between tricalcium phosphate ceramic and fetal bovine serum in crisscross.
(15) Rhesus monkey BAT mitochondria (BATM) possess an uncoupling protein that is characteristic of BAT as evidenced by the binding of [3H]GDP, the inhibition by GDP of the high Cl- permeability or rapid alpha-glycerol-3-phosphate oxidation.
(16) Incubation of I diaphragms with isoproterenol did not significantly increase the concentrations of AMP, IMP or inorganic phosphate, activators of phosphorylase beta activity, nor was there a decrease in ATP and glucose 6-phosphate content, allosteric inhibitors of phosphorylase beta activity.
(17) It is unclear if the changes in high-energy phosphates during endotoxin shock cause irreversibility.
(18) We tested the hypothesis that furosemide interferes with energy generation in the cochlea, and determined its effect on CO2 formation from glucose and glyceroaldehyde-3-phosphate dehydrogenase (GAPDH) activity by examining biochemical and histochemical changes in the cochlea, the kidney, and the liver.
(19) Several aminoacyl-tRNA synthetases are herein shown to catalyze the AMP----ADP and ADP----ATP exchange reactions (in the absence of tRNAs) by utilizing a transfer of the gamma-phosphate of ATP to reactive AMP and ADP intermediates that are probably the mixed anhydrides of the nucleotide and the corresponding amino acid.
(20) No difference in urinary sodium or potassium excretion was observed between SHR and WKY, but basal calcium and phosphate excretion were reduced in SHR (P less than 0.05).