Mineralization biological

Mineralization is the precipitation of calcium phosphate, but biochemical mediation of this process is not fully understood. In this chapter, the chemistry underlying mineralization (Sect. 1) and the structures ofbones and teeth (Sect. 2) are described. Osteoblasts secrete osteoid matrix and matrix vesicles that transport type I collagen and calcium phosphate, respectively, to the matrix where they will mineralize. Secreted matrix vesicles take up calcium and phosphate until they burst and release the calcium phosphate, which then redissolves and remineralizes around the type I collagen (Sect. 3). Glycoproteins involved in correctly modeling bone and dentin, and the role of osteocalcin in limiting excessive bone growth is then discussed (Sect. 4). There follows a detailed description of enamel (E) mineralization and of the major proteins involved (Sect. 5) followed by two summaries the difference between enamel and bone mineralization, and the vitamins required for mineralization (Sect. 6). 

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The biological mineralizing systems for iron that have been studied the most extensively are the ferrihydrite (and, in prokaryotic ferritins, the amorphous... 

Zipkin, I. (ed.) Biological Mineralization. New York-London-Sidney-Toronto John Wiley 1973... 

Halstead, L. B. Are mitochondria directly involved in biological mineralization The mitochondrion and the origin of bone. Calc. Tiss. Res. 3, 103 (1969)... 

Biodegradation. The biological mineralization of fixed nitrogen is well studied ammonia is oxidized to nitrite, and nitrite to nitrate, by autotrophic bacteria, and nitrate is reduced to nitrogen by anaerobic bacteria. On the other hand, ammonia and nitrate are essential nutrients for plant and bacterial growth, so one option is to use these organisms to take up and use the contaminants. 

In almost all instances of biological mineralization fibrous proteins represent the bulk of the organic matrix. In the past, this phenomenon has been interpreted to mean that proteins such as collagen, keratin or elastin are the key elements in mineralization by providing nucleation sites and at the same time offering structure and space for oriented crystal growth. However, with the advance in the field of biomineralization this model came under severe attack. At present, there is no universal concept which could explain all the intriguing facets of phosphate deposition in cellular systems. 

In conclusions, many schemes have been developed for metal ion — phosphate — organic matter interactions in biomineralization. A variety of organic compounds of the kind present in mineralized tissues were found to coordinate calcium ions at neutral or functional sites and in many instances metal ion coordination was accompanied by the binding of phosphate. Although a wealth of information exists on the organic-inorganic interplay, data could not be reduced to a point where a simple model on biological mineralization could be formulated. 

Herring, G. M. The mucosubstances of bone. In Biological mineralization (ed. I. Zipkin), pp. 75-94. New York-London-Sydney-Toronto John Wiley Sons 1973. 

There are three distinct biological minerals in an individual tooth, viz. enamel, dentin, and cementum. The chemical composition of dentin is quite similar to that of bone, containing 70 wt% of inorganic phase, 20 wt% of organic matrix and 10 wt% of water.83 The inorganic phase of tooth... 

The above observations clearly point towards diffusion control as potentially being an important component of the control process operating in biological mineralization. 

J. Garside, in "Biological Mineralization and Demineralization", ed. G. Nancollas. Springer Verlag, Berlin 1982. 

This comparison between inorganic processes and the more complex systems found in organisms will serve as a framework in our discussion of biological mineralization, and we shall make frequent reference to these processes in speaking of carbonate deposition by metazoa. The bases for dif-... 

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