Calcium phosphate capacity

Kato H, Shibano M, Saito T, et al. 1994. Relationship between hemolytic activity and adsorption capacity of aluminum hydroxide and calcium phosphate as immunological adjuvants for biologicals. Microbiol Immunol 38 543-548. 

In general, saliva (as well as plaque fluid) is supersaturated with respect to calcium-phosphate salts, and they prevent tendency to dissolve mineral crystals of teeth. Moreover, precipitation of calcium-phosphate salts that include hydroxyapatite may also occur (remineralization) in early lesions of tooth surfaces injured by acidic bacterial products (i.e., lactic acid). Salivary fluoride facilitates calcium-phosphate precipitation, and such crystals (i.e., fluorapatite) show lower acid solubility properties that lead to an increased caries preventive effect. The increase of pFI (i.e., buffer capacity and pH of saliva, as well as ureolysis in dental plaque) also facilitates crystal precipitation and remineralization (4, 13). 

The alteration of mineral and casein equilibria is reflected in changes to the physical properties of milk. The addition of citrate and different types of phosphates (ortho-, pyro-, or hexameta) to milk protein concentrate solutions, which alters the distribution of calcium and inorganic phosphate between the colloidal and serum phases of milk, affects its turbidity and buffering capacity (Mizuno and Lucey, 2005). The turbidity is affected because dissolution of colloidal calcium phosphate is accompanied by release of caseins into the serum. 

In sequestration (chelation) the hardness ions are bound to the builder in the form of soluble complexes. Phosphates, citrates, and nitrilotriacetic acid (NTA) are examples of this class of builder compound. Table 8.3 lists the calcium binding capacities of various builders. Other strongly chelating compounds exist, such as phosphonates and EDTA, but they are generally not extensively used in HDLDs. The most efficient builder is sodium tripolyphosphate (STPP). Unfortunately, tripolyphosphate has been identified as a possible cause of eutrophication in lakes and rivers. It is severely controlled and even banned in several countries. As a result, most countries in North America and Europe have converted to nonphosphate formulations. Other regions are also gradually imposing restrictions on the use of phosphates. 

Normal human serum actually contains two chromatographically distinct forms of ceruloplasmin. A calcium phosphate column cleanly separates major (I) and minor (II) components, the latter being approximately 15% of the total ceruloplasmin present in the serum (109—111). Ryden (112, 113) has shown that the two forms though identical in amino acid composition and Cu binding capacity, differ in the degree to which carbohydrate components have been affixed to the protein during biosynthesis. Most of the presently accepted physical properties of human ceruloplasmin are presented in Table 2. 

S.J. Roberts, L. Geris, G. Kerckhofs, E. Desmet, J. Schrooten, F.P. Luyten, The combined bone forming capacity of human periosteal derived cells and calcium phosphates. Biomaterials 32 (19) (2011) 4393-4405, doi 10.1016/j. biomaterials. 2011.02.047. 

Bioceramics have now been widely used as bone replacement materials in orthopaedic surgery. In particular, calcium phosphate ceramics have been applied as bioactive ceramics with bone bonding capacities. 

The casein phosphoproteins may be regarded collectively as calcium caseinate, but the number of Ca present can exceed the number of phosphoserine residues per casein molecule and the number required by stoichiometric calcium phosphate. This well-known binding capacity for excess calcium may be accommodated by attachment to ionised aspartyl or glutamyl residues present in the casein protein chains. Under some conditions, the presence of excess Ca leads to aggregation and precipitation of calcium caseinate complex (Chapter 10.2). 

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