Inorganic Phosphates and Phosphate Esters in Tissue Extracts

Griswold, Barbara; Humoller, Fred L.; McIntyre, A. R.

doi:10.1021/ac60049a041

Cited by 153 publications

(46 citation statements)

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“…2,3,25 It was also reported that organic phophorus and hydrolyzable phosphorus were converted into the orthophosphate ion for determining P-PO4 3-. 3,4,[25][26][27] In a previous report, the formation conditions of molybdophosphate and -arsenate complexes in aqueous solution were confirmed. 28 A few kinds of molybdophosphate complexes have been formed under high acidic conditions.…”

mentioning

confidence: 72%

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

2001

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Extensive studies have been devoted to the determination of phosphorus as phosphate ion by the molybdenum blue method. There have been many reports on various modifications of this method in order to make the sensitivity and stability high. Various reductants, such as 1-amino-2-naphthol-4-sulfonic acid, stannous chloride(II), and ascorbic acid have been used to reduce the molybdophosphate complex. 1-11 However, it is known to be difficult for methods using 1-amino-2-naphthol-4-sulfonic acid and stannous chloride(II) to control both the pH and the temperature. 12 It is also well known that solvent extraction with ethyl acetate, 1-butylalcohol, 2-methyl-1-propylalcohol, and so on, makes the sensitivity high. 5,[13][14][15][16][17][18][19][20][21] Motomizu et al. reported that the formation of colored ionassociate between molybdophosphate and Malachite Green could be utilized to determine phosphorus in the ultra-trace range from 0.018 to 1.0 ng cm -3 . 22These highly sensitive methods contain a few careful procedures and require skill to determine P-PO4 3-with both high accuracy and precision. Molybdenum blue methods containing other metal ions, such as Sb(III), so-called phosphoantimonylmolybdenum blue method, has also usually been used as manual batch procedures. 2,3,23 Blomqvist and Westin reported in detail the effect of Cr(VI), Ge(VI), W(VI), and V(V) ions that have easily reacted with heteropolyoxometalate on the absorbance measurement in the phosphoantimonylmolybdenum blue method. 24 Various flowinjection analysis methods, that analyze phosphorus automatically, have also been developed. 2,3,25 It was also reported that organic phophorus and hydrolyzable phosphorus were converted into the orthophosphate ion for determining P-PO4 3-. 3,4,[25][26][27] In a previous report, the formation conditions of molybdophosphate and -arsenate complexes in aqueous solution were confirmed. 28 A few kinds of molybdophosphate complexes have been formed under high acidic conditions. The addition of water-miscible organic solvents, such as acetonitrile and acetone, made only 12-molybdophosphate stable. Maeda et al. examined the electrochemistry of 12-molybdophosphate in aqueous-organic solution. 29 The reduced form of 12-molybdophosphate was found to be more stable in aqueousorganic solution than in aqueous solution. Based on these results, optimizing the formation conditions of the reduced 12-molybdophosphate complex in aqueous-organic solution seems to enable one to determine a wider range of concentrations of P-PO4 3-than the phosphoantimonylmolybdenum blue method as a manual batch procedure. ExperimentalThe absorption spectra were recorded on a Hitachi Model U-2000 spectrophotometer using silica cells with path lengths of 0.1 and 1 cm. Spectroscopic measurements under various conditions were made at 25 ± 0.1˚C without any baseline correction; those under the optimum determining conditions were made at room temperature. All of the reagents were of analytical grade, and were used as received. Results and Discussion Optimizatio...

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confidence: 72%

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

2001

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“…Oligomers were synthesized on a BioSearch 8600 synthesizer by standard cyanoethyl-phosphoramidite chemistry, followed by purification using reverse-phase high-pressure liquid chromatography (HPLC). Molar extinction coefficients (s) for the singlestranded oligomers were determined by phosphate analysis (15 Hairpin Polyamide Synthesis and Characterization. The polyamide, ImPyPy-,y-PyPyPy-f3-Dp (Fig.…”

Section: Methodsmentioning

confidence: 99%

Binding of a hairpin polyamide in the minor groove of DNA: sequence-specific enthalpic discrimination.

Pilch

Poklar²,

Gelfand³

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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Hairpin polyamides are synthetic ligands for sequence-specific recognition in the minor groove of doublehelical DNA. A thermodynamic characterization of the DNAbinding properties exhibited by a six-ring hairpin polyamide, ImPyPy-y-PyPyPy-P-Dp (where Im = imidazole, Py = pyrrole, y = -y-aminobutyric acid, ,B = ,I-alanine, and Dp = dimethylaminopropylamide), reveals an -1-2 kcal/mol greater affinity for the designated match site, 5'-TGTTA-3', relative to the single base pair mismatch sites, 5'-TGGTA-3' and 5'-TATTA-3'. The enthalpy and entropy data at 200C reveal this sequence specificity to be entirely enthalpic in origin. Correlations between the thermodynamic driving forces underlying the sequence specificity exhibited by ImPyPy-y-PyPyPy-f3-Dp and the structural properties of the heterodimeric complex of PyPyPy and ImPyPy bound to the minor groove of DNA provide insight into the molecular forces that govern the affinity and specificity of pyrrole-imidazole polyamides.

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“…the concentration of nitrogen in the supernatant after precipitation of the casein at pH 4.6 [12]. Inorganic phosphate was estimated by the method of Griswold et al [13], and calcium by complexometric titration [14]. The x-casein content of the micellar fractions was found by electrophoresis.…”

Section: Methodsmentioning

confidence: 99%

The Coagulation of Differently Sized Casein Micelles by Rennet

Dalgleish

Brinkhuis

Payens

1981

European Journal of Biochemistry

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Fractions of bovine casein micelles of different sizes were prepared by sucessive centrifugation steps, and dilute suspensions of the different fraction were reacted with rennet. The molecular weight increas with time after addition of rennet was measured by light scattering. After an initial lag stage, where the increase was zero, and a short intermediate stage, the molecular weight became linearly proportional to time, indicating complete conversion of the ϰ‐casein substrate by the enzyme. The slope of the final portion of the growth profile can be used to define values of the Smoluchowski rate constant governing the aggregation. No significant differences in this constant were found with mielles of different sizes, and the value of the rate constant suggested that the aggregation reaction of completely renneted micelles is only moderately retarded relative to the diffusion controlled process, even at room temperature.

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Inorganic Phosphates and Phosphate Esters in Tissue Extracts

Cited by 153 publications

References 4 publications

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

Binding of a hairpin polyamide in the minor groove of DNA: sequence-specific enthalpic discrimination.

The Coagulation of Differently Sized Casein Micelles by Rennet

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