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Phosphate Binding (phosphate + binding)

Distribution by Scientific Domains

Chemistry	75%

Selected Abstracts

Expanding Sapphyrin: Towards Selective Phosphate Binding

CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2008
Evgeny
Abstract The anion-templated syntheses and binding properties of novel macrocyclic oligopyrrole receptors in which pyrrole rings are linked through amide or imine bonds are described. The efficient synthesis was accomplished by anion-templated [1+1] Schiff-base condensation and acylation macrocyclization reactions. Free receptors and their host,guest complexes with hydrochloric acid, acetic acid, tetrabutylammonium chloride, and hydrogen sulfate were analyzed by single-crystal X-ray diffraction analysis. Stability constants with different tetrabutylammonium salts of inorganic acids were determined by standard 1H,NMR and UV/Vis titration techniques in [D6]DMSO/0.5,% water solution. According to the titration data, receptors containing three pyrrole rings (10 and 12) exhibit high affinity (log,Ka=5,7) for bifluoride, acetate, and dihydrogen phosphate, and interact weakly with chloride and hydrogen sulfate. The amido-bipyrrole receptors 11 and 13 with four pyrrole rings exhibit 104 - and 102 -fold selectivity for dihydrogen phosphate, respectively, as inferred from competitive titrations in the presence of tetrabutylammonium acetate. [source]

Effect of Iron(III) Chitosan Intake on the Reduction of Serum Phosphorus in Rats

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2000
JOSEPH BAXTER
Because of the widespread use of aluminium- and calcium-containing phosphate binders for the control of hyperphosphataemia in patients with end-stage renal failure, an iron(III) chitosan complex was synthesised and fed to rats to measure its effect on serum phosphorus and calcium, intestinal phosphate binding and phosphate absorption. Thirty-six Wistar rats were randomly selected and distributed into a baseline group (n = 6), a control group (n = 8 (days 0,15), n = 8 (days 16,30)) and a treatment group (n = 8 (days 0,15), n = 8 (days 16,30)). The control groups ingested AIN-76 diet mix with a 1% w/w fibre content; however, the treatment groups had the fibre content completely substituted with iron(III) chitosan. The mean weights of the treated rats were slightly lower from 15 days (not significant); but overall, rat growth was not stunted in the treatment groups. The serum phosphorus levels of the treated group (n = 8) were significantly reduced after 15 days (P = 0.004; control: 5.7 ± 0.9 mg dL,1; treatment: 4.4±0.5 mg dL,1; 95% CI of difference: 0.5,2.2) and 30 days (P = 0.002; control: 5.5 ± 0.9 mg dL,1; treatment = 4.1 ± 0.6 mg dL,1; 95% CI of difference: 0.6,2.3) as compared with the respective control group. The serum calcium-phosphorus product was 62.0 ± 12.1 mg2 dL,2 for the control and 45.1 ± 6.6 mg2 dL,2 for the treatment group after 30 days (P = 0.004). The serum iron concentration of the treatment group did not differ from the baseline value after 15 and 30 days, but the treatment group was significantly higher than the control group (P < 0.05) after 30 days. The faeces phosphorus levels (mg day,1) were higher (P < 0.01) and its iron content was much higher (P < 0.01) for the treated group. The urine phosphorus (mg kg,1) was not significantly reduced for the treated group, but the mean was consistently less. The kidney and liver weights of both groups were similar, but the phosphorus content of the kidney (mg (g kidney),1) was higher for the treated group after 30 days (P = 0.041; control, 4.2 ± 1.2 mg g,1 vs treatment, 5.6 ± 1.4 mg g,1. Because iron(III) chitosan had a high phosphorus-binding capacity of 308 (mg P) per gram of Fe3+ for both the in-vitro (pH 7.5) and in-vivo studies, which is greater than nearly all commonly used phosphate binders, and a small net phosphorus absorption difference of 3.7 mg day,1, it is an efficient phosphate binder for lowering serum phosphate levels without increasing serum calcium levels. [source]

Mapping nucleotide binding site of calcium ATPase with IR spectroscopy: Effects of ATP ,-phosphate binding

BIOPOLYMERS, Issue 4-5 2002
Man Liu
Abstract The changes in the IR spectra of the sarcoplasmic reticulum Ca2+ -ATPase upon nucleotide binding are recorded in H2O at 1°C in different buffers [imidazole, methylimidazole, 3-(N -morpholino)propanesulfonic acid, and phosphate] at different pH values (pH 6.5,7.8). The difference spectra of nucleotide binding are sensitive to the composition of the solvent. With methylimidazole at pH 7.5 providing the largest binding-induced signals, the effects of ,-phosphate binding are investigated using ATP, ADP, and ,,,-iminoadenosine 5,-triphosphate. The ,-phosphate contributes ,20% to the conformational change seen by IR spectroscopy and affects the ,-sheet structures. The IR experiments also reveal the known affinity difference between ADP and ATP. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 267,270, 2002 [source]