Studien zum Calciumstoffwechsel mit45Ca

Mattern, H.; Schreier, K

doi:10.1007/bf02116791

Cited by 7 publications

(1 citation statement)

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“…36 In other feeding experiments daily administration of 10 or 20 mg. of Graham's salts to rats for 10 days has no effect upon calcium uptake in bone and teeth. 64 More recent findings again indicate no adverse physiological effects when 0.5 and 1.2 per cent phosphorus as orthophosphate and sodium hexametaphosphate are fed to growing rats for 150 days. From autopsy, histological, and clinical studies it was concluded that there was adequate absorption and utilization of calcium, phosphorus, and iron.65 Some information pertaining to the physiological chemistry of the polyphosphates is found in studies related to the use of these materials to remove or to speed the biological turnover of undesirable radioelements.…”

Section: Inorganic Polyphosphatesmentioning

confidence: 92%

Biochemistry, Pharmacology, and Physiological Chemistry of Phosphates

Katchman

1964

J Dent Res

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Phosphorus, a universal constituent of protoplasm, is required for growth, health, and reproduction in all forms of plants and animals. It shares this important position in life processes with other elements such as nitrogen, oxygen, hydrogen, carbon, and sulfur. However, it differs in one aspect: its availability. Whereas N, 02, H, and C are readily available and accessible from the atmosphere, phosphorus is earthbound. The accessible phosphorus in the lithosphere occurs as phosphate minerals, all of which are orthophosphates. Thus, in an evolutionary sense, all forms of life have been restricted to the utilization of orthophosphate as a basic material. This is not too surprising in view of the fact that the orthophosphate structure is the most stable and the most preferred state of the element under conditions normal to the surface of the earth.Phosphates function in living systems both chemically and physically. The most notable chemical effect is the entrance of polyphosphate monoesters into chemical reactions so as to cause them to proceed. In other words, potentially endergonic reaction steps are replaced by exergonic reactions involving phosphates. This is discussed more fully in a later section. Other chemical actions of the phosphates in biology are pH buffering, formation of soluble complexes with cations, and precipitation of orthophosphate ions with calcium to give the highly insoluble hydroxylapatite which forms the basis of bones.The physical role of the phosphates is exemplified in the "lock-and-key" concepts of biology, where the phosphate groupings afford negatively charged sites on complicated molecular structures. Moreover, the polyphosphates give a highly localized concentration of negative charge, thereby greatly increasing the ionic strength within a volume of molecular dimensions. Related to these two ideas is the strong interaction between positively charged substances of high molecular weight and/or high charge (e.g., the proteins) with the polyphosphate anions. Another gross physical property of the phosphates is the mechanical strengthening of complicated living organizations through the formation of mineralized tissues.Presumably, emphasis in the future will shift from the ubiquity of the polyphosphates in biochemical reactions to their role in structural biochemistry. This will mean that the concepts of physical chemistry, including even quantum mechanical calculations, will become more important to biologists interested in phosphorus than is the descriptive chemistry of organic phosphates today. GLYCOLYSIS AND FERMENTATIONGreen plants are capable of converting light energy to chemical energy in situ, and non-photosynthesizing organisms obtain stored chemical energy by ingestion or absorption of foodstuffs. In either case, this stored chemical energy must be utilized in the chemical reactions underlying cell functions. These reactions involve the formation and breakdown of adenosine triphosphate or other phosphated organic compounds. Indeed, the key substance' which enables glucose to...

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Section: Inorganic Polyphosphatesmentioning

confidence: 92%