Determination of Phosphate by Differential Spectrophotometry

Gee, Allen; Deitz, Victor R.

doi:10.1021/ac60081a006

Cited by 203 publications

(72 citation statements)

References 19 publications

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“…Additional experiments were also carried out over a 4-h period using a larger sample volume (1.8 ml) that was stirred with a small magnetic stir bar. At the end of this time period, in selected experiments changes in total calcium and phosphate were determined using atomic absorption spectroscopy (AAnalyst 200, PerkinElmer Life Sciences) and a spectrometric method (8), respectively. Mineral phase identification was carried out using TEM in selected area electron diffraction (SAED) mode and Fourier transform-infrared (FT-IR) spectroscopy.…”

Section: Methodsmentioning

confidence: 99%

Role of 20-kDa Amelogenin (P148) Phosphorylation in Calcium Phosphate Formation in Vitro

Kwak¹,

Bidlack²,

Beniash

et al. 2009

Journal of Biological Chemistry

102

152

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The potential role of amelogenin phosphorylation in enamel formation is elucidated through in vitro mineralization studies. Studies focused on the native 20-kDa porcine amelogenin proteolytic cleavage product P148 that is prominent in developing enamel. Experimental conditions supported spontaneous calcium phosphate precipitation with the initial formation of amorphous calcium phosphate (ACP). In the absence of protein, ACP was found to undergo relatively rapid transformation to randomly oriented plate-like apatitic crystals. In the presence of non-phosphorylated recombinant full-length amelogenin, rP172, a longer induction period was observed during which relatively small ACP nanoparticles were transiently stabilized. In the presence of rP172, these nanoparticles were found to align to form linear needle-like particles that subsequently transformed and organized into parallel arrays of apatitic needle-like crystals. In sharp contrast to these findings, P148, with a single phosphate group on serine 16, was found to inhibit calcium phosphate precipitation and stabilize ACP formation for more than 1 day. Additional studies using non-phosphorylated recombinant (rP147) and partially dephosphorylated forms of P148 (dephoso-P148) showed that the single phosphate group in P148 was responsible for the profound effect on mineral formation in vitro. The present study has provided, for the first time, evidence suggesting that the native proteolytic cleavage product P148 may have an important functional role in regulating mineralization during enamel formation by preventing unwanted mineral formation within the enamel matrix during the secretory stage of amelogenesis. Results obtained have also provided new insights into the functional role of the highly conserved hydrophilic C terminus found in full-length amelogenin.Extracellular matrix molecules play a crucial role in the regulation of biological mineralization by controlling crystal size, shape, and organization. An example of this exquisite regulation is in the formation of the highly organized dental enamel tissue that is regulated in part by amelogenin, the major extracellular matrix protein secreted by ameloblasts (1). Although amelogenin is processed by proteinases soon after secretion, the intact full-length parent molecule has been found to be exclusively associated with newly formed enamel mineral (2). Prior studies in our laboratory (3) have also shown that fulllength recombinant mouse amelogenin (rM179) can regulate the formation of parallel arrays of apatitic crystals (a salient feature of developing and mature dental enamel) under conditions of spontaneous precipitation in vitro. This functional capability appears to be related to the specific primary structure of the full-length amelogenin and its unique assembly properties under certain physicochemical conditions of pH and temperature (4). In particular, the conserved hydrophilic C terminus of amelogenin has been shown to play a key role in these processes (3).To date, however, most studies have utilized r...

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Section: Methodsmentioning

confidence: 99%

Role of 20-kDa Amelogenin (P148) Phosphorylation in Calcium Phosphate Formation in Vitro

Kwak¹,

Bidlack²,

Beniash

et al. 2009

Journal of Biological Chemistry

102

152

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“…Calcium content of ashed skeletal samples was determined by atomic absorption spectrometry and phosphate by the method of Gee and Deitz (4). Carbonate content of deproteinated samples was determined by a modified microdiffusion technique (5).…”

Section: Methodsmentioning

confidence: 99%

Abnormal Bone Mineral Maturation in the Chronic Uremic State

Russell¹,

Termine²,

Avioli³

1973

J. Clin. Invest.

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A B S T R A C T X-ray diffraction analysis of bone from chronically uremic but nonacidotic rats with normocalcemia and hyperphosphatemia revealed smaller apatite crystals and an increase in the X-ray amorphous mineral fraction when compared to age-matched, pair-fed control animals, indicating less advanced mineral maturation in the uremic animals. Studies in animals with varied degrees of chronic renal insufficiency revealed a progression of the bone crystal maturational defect with advancing uremia. INTRODUCTIONAlthough a causal relationship between chronic renal failure and progressive osteopenia has been well documented by radiographic and histochemical analyses (1, 2), the sequence of physiology and biochemical events that initiate and perpetuate the derangements in skeletal metabolism are still poorly defined. Previous investigations have been concerned primarily with rates of bone mineral (apatite) and matrix (collagen) turnover, under the assumption that the intricate processes of crystal growth and collagen maturation were proceeding in normal fashion. In an earlier study, we demonstrated maturational alterations in bone collagen and mineral metabolism in the experimental uremic state that progressed with advancing uremia, although insignificant alterations in plasma pH, calcium, and bone carbonate content obtained (3). The present study was undertaken to determine whether the apparent collagen maturational defect in the advancing uremic state is associated with compositional and structural alterations of the mineral

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“…The (Ca + Mg)/P molar ratios in the as-prepared powders were evaluated by a chemical analysis [23,24]. The fluoride content was measured using a fluoride selective electrode (Ingold, PF4-L).…”

Section: Powder Characterizationmentioning

confidence: 99%

Sintering and Mechanical Properties of Magnesium and Fluorine Co-Substituted Hydroxyapatites

Nsar¹,

Hassine²,

Bouzouita³

2013

JBNB

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Biological apatites contain several elements as traces. In this work, magnesium and fluorine co-substituted hydroxyapatites with the general formula Ca 9 Mg(PO 4 ) 6 (OH) 2-y F y , where y = 0, 0.5, 1, 1.5 and 2 were synthesized by the hydrothermal method. After calcination at 500˚C, the samples were pressureless sintered between 950˚C and 1250˚C. The substitution of F − for OH − had a strong influence on the densification behavior and mechanical properties of the materials. Below 1200˚C, the density steeply decreased for y = 0.5 sample. XRD analysis revealed that compared to hydroxylfluorapatite containing no magnesium, the substituted hydroxyfluorapatites decomposed, and the nature of the decomposition products is tightly dependent on the fluorine content. The hardness, elastic modulus and fracture toughness of these materials were investigated by Vickers's hardness testing. The highest values were 622 ± 4 GPa, 181 ± 1 GPa and 1.85 ± 0.06 MPa·m 1/2 , respectively.

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Determination of Phosphate by Differential Spectrophotometry

Cited by 203 publications

References 19 publications

Role of 20-kDa Amelogenin (P148) Phosphorylation in Calcium Phosphate Formation in Vitro

Role of 20-kDa Amelogenin (P148) Phosphorylation in Calcium Phosphate Formation in Vitro

Abnormal Bone Mineral Maturation in the Chronic Uremic State

Sintering and Mechanical Properties of Magnesium and Fluorine Co-Substituted Hydroxyapatites

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