Calcium biological importance

The number of elements that are known to be biologically important comprises a relatively small fraction of the 109 known elements. Natural abundance limits the availability of the elements for such use. Molybdenum (Z = 42) is the heaviest metal, and iodine (Z = 53) is the heaviest nonmetal of known biological importance. The metals of importance in enzymes are principally those of the first transition series, and the other elements of importance are relatively light sodium, potassium, magnesium, calcium, carbon, nitrogen, phosphorus, oxygen, chlorine, and, of course, hydrogen. 

Certain dipositive metal ions not only accelerate the hydrolysis of ATP, as mentioned above, but also assist in the transfer of a phosphoryl group from one molecule to another. Such a nonenzymatic transphosphorylation takes place between ATP and an orthophosphate ion or its monoester in the presence of calcium(II), cadmium(II), and manganese(II). This type of nonenzymatic process can serve as a model for the biologically important enzymatic transphosphorylations that involve ATP, although... 

Phosphorus is required not only as a component of hydroxyapatite in bone, but also as a component of nucleic acids and many other biologically important molecules. Without phosphorus we would have no energy-storage molecules, such as ATP and creatine phosphate, for the energy derived from glycolysis and the citric acid cycle. The RDA for phosphorus is the same as that for calcium. Because it is abundant in most foods, a deficiency of phosphorus in the presence of an otherwise adequate diet is virtually impossible. 

In addition to these most important uses of gel chromatography some further applications may be mentioned. If we are interested in the degree of purity of a substance in a crude extract or in the course of purification, i.e., if we wish to determine the extent to which it is contaminated by substances of other values, GPC can be used to determine the purity of the product. In substances possessing the same biological importance or effect, their diversity (or identity) may be determined by GPC. This approach has been employed, e.g., for the characterization of calcium-binding proteins in different organs [49], in the study of isoenzymes... 

Calmodulin is a calcium-binding protein that regulates several biologically important processes by interacting with various proteins. This protein was targeted with a disulfide-based DCL in a pre-equilibrated strategy [52]. A DCL generated from five cysteine-based derivatives was allowed to interact with the protein in the... 

This compound has not one, but two chiral centers. Both the inner carbon atoms are attached to four different groups. Tartaric acid is found in nature as the free acid, as a salt of calcium or potassium, in fruit extracts, and especially as crystals deposited during wine fermentation. The naturally occurring form is optically active in solution. Tartaric acid is typical many biologically important molecules are chiral. In Section 25.9 we will examine the amino acids, all of which (except for glycine) are chiral and found in nature as just one of the enantiomers. 

The pioneering work of Ross Adey s group identified the frequency window for calcium ion, and further ion cyclotron resonance method proposed by Abe Liboff [12] identified resonance frequencies for a number of biologically important ions. 

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