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At least 37 records · Page 2Linked to original sources
PubMed2006

Sorption dynamics of organic and inorganic phosphorus compounds in soil.

Phosphorus retention in soils is influenced by the form of P added. The potential impact of one P compound on the sorption of other P compounds in soils has not been widely reported. Sorption isotherms were utilized to quantify P retention by benchmark soils from Indiana, Missouri, and North Carolina when P was added as inorganic P (Pi) or organic P (beta-D-glucose-6-phosphate, G6P; adenosine 5'-triphosphate, ATP; and myoinositol hexaphosphate, IP6) and to determine whether soil P sorption by these organic P compounds and Pi was competitive. Isotherm supernatants were analyzed for pH and total P using standard protocols, while Pi and organic P compounds were assayed using ion chromatography. Under the controlled conditions of this study, the affinity of all soils for P sources followed the order IP6 > G6P > ATP > Pi. Each organic P source had a different potential to desorb Pi from soils, and the order of greatest to least Pi desorption was G6P > ATP > IP6. Glucose-6-phosphate and ATP competed more directly with Pi for sorption sites than IP6 at greater rates of P addition, but at the lesser rates of P addition, IP6 actually desorbed more Pi. Inositol hexaphosphate was strongly sorbed by all three soils and was relatively unaffected by the presence of other P sources. Decreased total P sorption due to desorption of Pi can be caused by relatively small additions of organic P, which may help explain vertical P movement in manured soils. Sorption isotherms performed using Pi alone did not accurately predict total P sorption in soils.

Adsorption↗
PubMed2000

Quenching of a photosensitized dye through single-electron transfer from trivalent phosphorus compounds

Various types of trivalent phosphorus compounds 1 undergo single-electron transfer (SET) to the photoexcited state of rhodamine 6G (Rho+*) in aqueous acetonitrile to quench the fluorescence from Rho+*. The rate constants kp for the overall SET process were determined by the Stern-Volmer method. The rate is nearly constant at a diffusion-controlled limit in the region of E1/2(1) < 1.3 V (vs Ag/Ag+), whereas log kp depends linearly on E1/2(1) in the region of E1/2(1) > 1.3 V, the slope of the correlation line being -alphaF/RT with alpha = 0.2. The potential at which the change in dependence of log kp on E1/2(1) occurs (1.3 V) is in accordance with the value of E1/2(Rho+*) (1.22 V) that has been obtained experimentally. Thus, the SET step is exothermic when E1/2(1) < 1.3 V and endothermic when E1/2(1) > 1.3 V. The alpha-value (0.2) obtained in the endothermic region shows that the SET step from 1 to Rho+* is irreversible in this region. Trivalent phosphorus radical cation 1*+ generated in the SET step undergoes an ionic reaction with water in the solvent rapidly enough to make the SET step irreversible. In contrast, the SET from amines 2 and alkoxybenzenes 3 to Rho+* is reversible when the SET step is endothermic, meaning that the radical cations 2*+ and 3*+ generated in the SET step undergo rapid "back SET" in the ground state to regenerate 2 and 3.

Journal Article↗
PubMed1993

Calcium ion dependent interaction of inorganic phosphorus compounds with phosphatidylcholine.

The translocation of orthophosphate, pyrophosphate, and polyphosphate into an organic phase was examined by means of the two-phase partition method. When the organic phase contained phosphatidylcholine (PtdCho), the phosphorus compounds translocated from the water-phase into the organic phase, depending on the concentrations of PtdCho and Ca2+, and the pH of the solution. Calcium ions were essential for the translocation. The concentration of Ca2+ necessary for the translocation appeared to depend on the molar concentration of the phosphorus compounds. Orthophosphate was translocated above pH 6.5, while pyrophosphate was translocated above pH 3.5. In contrast, polyphosphate was translocated in the whole pH range examined (pH 2.5-9.0), although approx. 9% of the total polyphosphate remained in the water-phase even at alkaline pH. These results suggest that phosphorus compounds can interact with PtdCho when the phosphorus compounds have formed complexes with Ca2+.

Calcium↗
PubMed1970

Acid-soluble phosphorus compounds in mammalian semen.

1. A method is described for the extraction, purification and separation of acid-soluble phosphorus compounds from mammalian semen. [8-(14)C]ATP and [8-(14)C]AMP were used as internal recovery standards to measure the breakdown and loss of these nucleotides in the procedure. 2. Bull, ram, boar and stallion semen was separated into seminal plasma and spermatozoa and the two fractions were examined separately. The overall composition of the mixture of the phosphorus compounds extracted from the two fractions was similar for the four species. 3. Glycerylphosphorylcholine and glycerylphosphorylinositol were the two phosphorus compounds identified in extracts of seminal plasma. ATP, ADP, AMP, GTP, GDP, NAD, fructose 1,6-diphosphate and glucose 6-phosphate were identified in extracts prepared from spermatozoa.

Adenine Nucleotides↗
PubMed1964

ACCUMULATION OF PHOSPHORUS COMPOUNDS BY MUCOR RACEMOSUS.

James, A. W. (The Pennsylvania State University, University Park), and L. E. Casida, Jr. Accumulation of phosphorus compounds by Mucor racemosus. J. Bacteriol. 87:150-155. 1964.-In glucose-inorganic salts media containing excess KH(2)PO(4), Mucor racemosus accumulated 5 to 6% phosphorus on a dry-weight basis in its mycelium. Fractionation of phosphorus compounds in young, rapidly growing mycelium revealed that approximately 58% of this phosphorus was in the form of inorganic polyphosphate; nucleic acids accounted for an additional 17% of the total phosphorus. Upon further growth, morphological changes were observed in many of the hyphae, and polyphosphate appeared in the culture media. In media containing limited amounts of KH(2)PO(4), exogenous polyphosphate was utilized by M. racemosus, and the phosphorus content of the mycelium decreased to approximately 0.3%.

Culture Media↗