Hydroxylapatite concentration

The only element that was discovered in body fluids (urine). This is plausible, as P plays a main role in all life processes. It is one of the five elements that make up DNA (besides C, H, N, and 0 evolution did not require anything else to code all life). The P-O-P bond, phosphoric acid anhydride, is the universal energy currency in cells. The skeletons of mammals consists of Ca phosphate (hydroxylapatite). The element is encountered in several allotropic modifications white phosphorus (soft, pyrophoric P4, very toxic), red phosphorus (nontoxic, used to make the striking surface of matchboxes), black phosphorus (formed under high pressures). Phosphates are indispensable as fertilizer, but less desirable in washing agents as the waste water is too concentrated with this substance (eutrophication). It has a rich chemistry, is the basis for powerful insecticides, but also for warfare agents. A versatile element. 

Hydroxylapatite Hybridization. Hydroxylapatite (HA) is a form of calcium phosphate that preferentially binds double-stranded DNA when in an appropriate concentration of phosphate buffer 21,22 This specificity provides a means for separating renatured DNA duplexes from free-solution reassociation reactions. Brenner et al.21 developed a batch procedure that allows handling of up to 10 samples at the same time, thus greatly increasing the utility of HA for DNA hybridizations. The procedure given here was derived from the work of Brenner et al.21 and Price et al.6... 

Despite the range in the absolute concentrations of Ca and P, Figure 1 indicates that for the most part the Ca/P ratios are nearly those expected for the dilution of hydroxylapatite, which has a weight ratio of 2.16. The straight line in Figure 1 is that expected for the simple dilution of hydroxyl-... 

The technique described for the purification of sheep polyclonal IgG by FPLC is easily applied to the purificadon of rodent MAbs. Rodent MAbs are easily prepared as an ascitic fluid, which, like a polyclonal serum, should be ammonium sulfate cut at 45% final concentration prior to final application to the FPLC column. Some workers have used hydroxyapatite (hydroxylapatite) for the purification of murine MAbs, but the authors have not found this to be very effective in most cases. 

Hydroxyapatite. This can be obtained from many sources (hydrox-ylapatite, BDH Chemicals Ltd., Poole, Dorset, U. K. BioGel HT, Bio-Rad Laboratories, Richmond, California), or it can be prepared in the laboratory. Our experience is limited to hydroxylapatite from BDH Chemicals, which is supplied in 50 mM phosphate buffer, pH 7.0. Before use, it was resuspended in 5 mM phosphate buffer, pH 7.0, or in Trisfhy-droxymethyl)methylamine-hydrochloric acid (Tris-HCl) buffer, pH 7.5, at a concentration of approximately 1 g/ml. It can also be used as an acetone-dried powder in a similar fashion to that described for Florisil. ... 

Figure 9 Plots showing the calculated mineral saturation indices as a function of pH for hydroxylapatite, quartz, and various asbestos-forming minerals in electrolyte solutions approximating the electrol)he compositions of lung fluids (approximated by interstitial fluids, upper plot) and intracellular fluids (lower plot). Electrolyte concentrations used as input were taken from Table 4. The CO2 partial pressure was fixed at the value for venous plasma for each speciation at a different pH. Organic species such as amino acids and other organic acids were not included in the calculations, but likely would have the effect of decreasing the calculated saturation indices somewhat due to their...

Example 7.18. Conversion of Calcite into Apatite Under what condition (pH, concentration of inorganic P) can calcite be converted into hydroxylapatite The simplifying assumptions Pj [Ca " ] and [Ca ] = Cj may be used. 

Cystalline hydroxylapatite [Cai0 (P04)6 (OH)2] is an adsorbent used to separate mixtures of proteins or nucleic acids. The mechanism of adsorption is not fully understood but is thought to involve both the calcium ions and phosphate ions on the surface and to involve dipole-dipole interactions and possibly electrostatic attractions. One of the most important applications of hydroxylapatite chromatography is the separation of single-stranded from double-stranded DNA. Both forms of DNA bind at low phosphate buffer concentrations but as the buffer concentration is increased further, double-stranded DNA is released. The affinity... 

Baravelli S, Bigi A, Ripamonti A, Roveri N, Forest E (1984) Thermal behavior of bone and synthetic hydroxylapatites submitted to magnesium interaction in aqueous medium. J Inorg Biochem 20 1-12 Barralet J, Best S, Bonfield W (1998) Carbonate substitution in precipitated hydroxylapatite an investigation into the effects of reaction temperatme and bicarbonate ion concentration. J Biomed Mater Res 41 79-86... 

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