Functions of Magnesium

Functions of Magnesium In plants, the main physiological role of magnesium is its contribution to the function of chlorophyll, though many other biochemical pathways have a need for magnesium. 

In general, magnesium is involved in the action of several hundreds of enzymes. 

Principally, it is necessary to distinguish between the intracellular and extracellular actions of magnesium  

Magnesium deficiency in humans poses a significant health hazard. Possible causes of 

Clinically relevant magnesium deficiency occurs in humans with  

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Fig. 12 Tensile strength of calcium sulfate tablets as a function of magnesium stearate concentration (solid fraction = 0.57). (From Ref. 29.)...

Figure 2 is a plot of the correction parameter C as a function of magnesium concentration and pH. Note that for the typical range of limestone scrubber inlet liquor pH, 5.2 to... 

Figure 2. Correction parameter C as a function of magnesium concentration and...

Figure 4. Dissolved sulfite concentration as a function of magnesium concentration and chloride-to-magnesium ratio for liquors saturated with calcium sulfite and gypsum at pH 5.5 and 50°C...

Ki (ure 10.1 Dielectric functions of magnesium oxide. Infrared data are from Jasperse et al. (1966) visible and ultraviolet data are from Roessler and Walker (1967). 

The function of magnesium in enzyme activity may either be to form a complex with the substrate, as in the magnesium-ATP complex formed in creatine kinase and phosphofhictokinase, or to bind to the enzyme and either produce an allosteric activation or play a direct role in catalysis. If an enzyme is known to utilize a nucleotide as one of its substrates, it can be assumed that magnesium is also required for catalysis. The magnesium ion possibly acts as an electrostatic shield. The enzyme pyravate kinase, described earlier, and shown in Figure 1, requires both magnesium and potassium ions for maximal activity. 

Figure 5.9 Salt rejection and flux of NF-40 membrane as a function of magnesium sulfate concentration and feedwater pressure.

Heaton FW (1993) Distribution and function of magnesium within the cell. In Birch NJ, ed. Magnesium and the cell, pp. 121-136. Academic Press, London. 

Nucleoside diphosphate kinases exhibit activity over a wide pH range, but usually have optima at or near pH 7. They require the presence of divalent metals for activity, but have a low specificity in this respect, since Mg +, Mn +, Ca +, Co +, and to a lesser extent, Ni + and Zn +, may satisfy this requirement. Magnesium is evidently the physiological ion serving this enzyme s requirement for a divalent ion. The function of magnesium ion in the nucleoside diphosphate kinase reaction is apparent in the work of Colomb et al. (27), who have shown that for the enzyme from beef heart mitochondria, MgATP, but not free ATP, serves as the phosphate donor. Further, free ADP was shown to be preferred over MgADP as the phosphate acceptor. 

Absorption, Metabolism, Excretion Functions of Magnesium Deficiency Symptoms Interrelationships... 

As shown in Fig. 3, they studied the formation of cholesterol ester With time in rat liver microsomes in imidazole buffer. As can be seen, in the presence of magnesium there was a considerable decline in the amount of cholesterol ester formed, but that it could be completely prevented or blocked if potassium fluoride and EDTA were included in the incubation mixture. In a sepairate experiment, they studied cholesterol ester formation as a function of magnesium ion concentration in the medium. Again, the ACAT activity declined with increasing magnesium in the medium, whereas inclusion of EDTA together with magnesium, stabilized the enzyme activity. This information is consistent with the data from our laboratory which demonstrates the presence in microsomes of a Mg++ sensitive phosphatase which inactivates 7a-hydroxylase. 

Figure 11.6 The burn rate of Mg/PTFE/RP obscurant as a function of magnesium content at the PTFE level (17wt%)...

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