Partition of calcium, phosphate, and protein in the fluid phase aspirated at calcifying sites in epiphyseal cartilage

Howell, David S.; Pita, Julio C.; Marquez, Juan F.; Madruga, Juan E.

doi:10.1172/jci105801

Cited by 169 publications

(67 citation statements)

References 22 publications

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“…The enhancement of the activity at this pH, however, is not particularly pronounced as compared to lower more physiological values, both in the absence or in the presence of ions. Howell et al [13] have shown that the extracellular fluid of epiphyseal cartilage has pH 7.8. Thus from our graph a good activity of alkaline phosphatase appears possible, not considering of course the influence of the type of substrate and of its concentration.…”

Section: Resultsmentioning

confidence: 99%

Alkaline phosphatase activity associated to a calcium binding glycoprotein from calf scapula cartilage

Vittur

Bernard

1973

FEBS Letters

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Section: Resultsmentioning

confidence: 99%

Alkaline phosphatase activity associated to a calcium binding glycoprotein from calf scapula cartilage

Vittur

Bernard

1973

FEBS Letters

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“…5 (42,43). For most of the studies, the pH of SCL was adjusted to 7.5, the pH observed in the extracellular fluid of growth plate cartilage (24,44). However, for the study of the role of ACP in unwashed and mild acid-washed PS-CPLX, the pH of the SCL was adjusted to various pH levels from 7.0 to 8.6 (see below).…”

Section: Methodsmentioning

confidence: 99%

Analysis and Molecular Modeling of the Formation, Structure, and Activity of the Phosphatidylserine-Calcium-Phosphate Complex Associated with Biomineralization

Genge

Wuthier

2008

Journal of Biological Chemistry

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The nucleational core of matrix vesicles contains a complex (CPLX) of phosphatidylserine (PS), Ca 2؉ , and inorganic phosphate (P i ) that is important to both normal and pathological calcification. Factors required for PS-CPLX formation and nucleational activity were studied using in vitro model systems and molecular dynamic simulations. Ca 2؉ levels required for and rates of PS-CPLX formation were monitored by light scattering at 340 nm, assessing changes in amount and particle size. Fourier transform infrared spectroscopy was used to explore changes in chemical structure and composition. Washing with pH 5 buffer was used to examine the role of amorphous calcium phosphate in CPLX nucleational activity, which was assessed by incubation in synthetic cartilage lymph with varied pH values. Addition of 4 Ca 2؉ /PS was minimally required to form viable complexes. During the critical first 10-min reaction period, rapid reduction in particle size signaled changes in PS-CPLX structure. Fourier transform infrared spectroscopy revealed increasing mineral phosphate that became progressively deprotonated to PO 4 3؊ . This Ca 2؉ -mediated effect was mimicked in part by increasing the Ca 2؉ /PS reaction ratio. Molecular dynamic simulations provided key insight into initial interactions between Ca 2؉ and P i and the carboxyl, amino, and phosphodiester groups of PS. Deduced interatomic distances agreed closely with previous radial distribution function x-ray-absorption fine structure measurements, except for an elongated Ca 2؉ -N distance, suggesting additional changes in atomic structure during the critical 10-min ripening period. These findings clarify the process of PS-CPLX formation, reveal details of its structure, and provide insight into its role as a nucleator of crystalline calcium phosphate mineral formation. One of the essential features of mineral-inducing matrix vesicles (MV)2 is the presence of a nucleation core (1, 2) that contains lipid-calcium-phosphate complexes (CPLX) capable of inducing mineral formation when incubated in a synthetic cartilage lymph (SCL) (3-6). A critical component of CPLX is the acidic phospholipid, phosphatidylserine (PS) (3,7,8), which is known to have a high affinity for Ca 2ϩ (9,10). PS is largely confined to the inner leaflet of the MV membrane (11), and electron micrographs of calcifying MV show the electrondense calcium phosphate precipitate juxtaposed along the inner leaflet of the MV membrane (12).Discovery of the nucleation core stems from the early finding that acidic phospholipids, especially PS, are complexed with Ca 2ϩ at sites of early mineralization (13,14). PS-Ca 2ϩ -P i complexes (PS-CPLX) are present at the early stages of almost all calcifying tissues as follows: growth plate cartilage (14), tumors (15), bone (16), and especially MV (8). Synthetic PS-CPLX formed in the absence of Mg 2ϩ has been found to be a powerful nucleator that rapidly induces hydroxyapatite (HA) formation when incubated in SCL (3, 4); however, when formed from Mg 2ϩ -and HCO 3 Ϫ -containing P i -r...

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“…The measured amount of secreted ATP in solution by murine osteoblast-like cell in response to shear was in the order of 100 nM, however this does not accurately show the local ATP concentration at the cell surface immediately on its release (38). In addition, the osteoblasts have been shown to express an membrane-bound ecto-nucleoside diphosphokinase (ecto-NDPK), which allows the ADPuATP conversion in extracellular calcification medium (35). Because of the physiological role of extracellular ATP in bone formation and remodeling, and its persisting presence in the calcification environment, ATP is expected to be one of the main sources of both P i and PP i , which play opposite roles in bone formation and remodeling.…”

mentioning

confidence: 99%

“…The nucleotide concentration of the extracellular fluid aspirated from the hypertrophic zone of rat calcifying epiphyseal cartilage was reported to reach 1-2 mM (34). Nucleotides (ATP/UTP) are also released both by non-stimulated (35,36) or stimulated osteoblasts (37,38) in response to mechanical stimulus. The measured amount of secreted ATP in solution by murine osteoblast-like cell in response to shear was in the order of 100 nM, however this does not accurately show the local ATP concentration at the cell surface immediately on its release (38).…”

mentioning

confidence: 99%

Phosphodiesterase Activity of Alkaline Phosphatase in ATP-initiated Ca2+ and Phosphate Deposition in Isolated Chicken Matrix Vesicles

Zhang

Balcerzak

Radisson

et al. 2005

Journal of Biological Chemistry

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Inorganic pyrophosphate is a potent inhibitor of bone mineralization by preventing the seeding of calcium-phosphate complexes. Plasma cell membrane glycoprotein-1 and tissue nonspecific alkaline phosphatase were reported to be antagonistic regulators of mineralization toward inorganic pyrophosphate formation (by plasma cell membrane glycoprotein-1) and degradation (by tissue nonspecific alkaline phosphatase) under physiological conditions. In addition, they possess broad overlapping enzymatic functions. Therefore, we examined the roles of tissue nonspecific alkaline phosphatase within matrix vesicles isolated from femurs of 17-dayold chick embryos, under conditions where these both antagonistic and overlapping functions could be evidenced. Addition of 25 M ATP significantly increased duration of mineralization process mediated by matrix vesicles, while supplementation of mineralization medium with levamisole, an alkaline phosphatase inhibitor, reduces the ATP-induced retardation of mineral formation. Phosphodiesterase activity of tissue nonspecific alkaline phosphatase for bis-p-nitrophenyl phosphate was confirmed, the rate of this phosphodiesterase activity is in the same range as that of phosphomonoesterase activity for p-nitrophenyl phosphate under physiological pH. In addition, tissue nonspecific alkaline phosphatase at pH 7.4 can hydrolyze ADPR. On the basis of these observations, it can be concluded that tissue nonspecific alkaline phosphatase, acting as a phosphomonoesterase, could hydrolyze free phosphate esters such as pyrophosphate and ATP, while as phosphodiesterase could contribute, together with plasma cell membrane glycoprotein-1, in the production of pyrophosphate from ATP.

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Partition of calcium, phosphate, and protein in the fluid phase aspirated at calcifying sites in epiphyseal cartilage

Cited by 169 publications

References 22 publications

Alkaline phosphatase activity associated to a calcium binding glycoprotein from calf scapula cartilage

Alkaline phosphatase activity associated to a calcium binding glycoprotein from calf scapula cartilage

Analysis and Molecular Modeling of the Formation, Structure, and Activity of the Phosphatidylserine-Calcium-Phosphate Complex Associated with Biomineralization

Phosphodiesterase Activity of Alkaline Phosphatase in ATP-initiated Ca2+ and Phosphate Deposition in Isolated Chicken Matrix Vesicles

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