Magnesium protein complex

Lau et al. [188] have shown that calcium ions are linked to phospholipids. The binding of calcium with hpids inhibits the formation of lipid/protein complexes. The decrease in mineral salts, particularly in magnesium and calcium ions, during processes 2 and 3 promotes the lipid/protein complexes formation. This phenomenon was confirmed by higher precipitation levels for lipids and proteins in process 3 in comparison with process 1 (Table 21.11). Equation 21.1 also means that an increase of components should improve the lipid/protein complexes formation. This increase of may be obtained by a concentration step of whey solutions by ultrafiltration. 

Magnesium porphyrin complexes called chlorophyll (Chi, 12) play important roles in photosynthesis in green plants and some bacteria. In green plants the chloroplasts of the thylakoid membrane contain macromolecular anisotropically oriented protein complexes with photosystems II and I (Fig. 2-26). 

As described above, the formation of xanthan-protein complexes induced by salts such as calcium or magnesium chloride depends strongly on the quality of the solution. It was previously reported that when xanthan solutions contained less impurities, interactions between macromolecules and calcium ions were less important, and that the pH limit corresponding to precipitation was shifted to basic pH (75). Here, when xanthan C broth was centrifuged, thixotropic phenomena were less apparent. So, for this xanthan solution, it is clearly shown that the presence of cellular components was essential to induce interactions between xanthan chains and cations. It can also be noted that the xanthan broth was frozen before all the experiments and thus, that the cells may have been lysed thereby releasing all their constituents inside the medium. Because of the diversity and complexity of the cellular components, it is difficult to predict which kind of interactions can be involved in the aggregation. 

A kinetic study on the activation of deoxyribonuclease I by magnesium has shown that the activation curve is biphasic (the substrate being the Mg salt of bovine spleen DNA). This indicates that activation occurs at two sites on the protein. Free Mg + was required for enzyme activity, confirming that a metallo-enzyme as well as a metallo-substrate is necessary for deoxyribonuclease I activity. In contrast, it has been shown that the pyrophosphatase activity of bovine brain alkaline phosphatase depends on Mg + bound to the enzyme but not on the formation of a magnesium-substrate complex. 

Figure 7-15 shows the time evolution of the temperature, total energy, and potential energy for a 300 ps simulation of the tetracycline repressor dimer in its induced (i.e., hgand-bound) form. Starting from the X-ray structure of the monomer in a complex with one molecule of tetracycline and a magnesium ion (protein database... 

A 0-9% salt solution is considered to be isotonic with blood. Other electrolytes present include bicarbonate ions (HCOj ) and small amounts of potassium, calcium, magnesium, phosphate, sulphate and organic acid ions. Included among the complex compounds and present in smaller amounts are phospholipids, cholesterols, natural fats, proteins, glucose and amino acids. Under normal conditions the extracellular body fluid is slightly alkaline with a pH of 7-4. ... 

There are problems as well in the absorption of certain drugs in the presence of specific food components. L-Dopa absorption may be inhibited in the presence of certain amino acids formed from the digestion of proteins [43], The absorption of tetracycline is reduced by calcium salts present in dairy foods and by several other cations, including magnesium and aluminum [115-117], which are often present in antacid preparations. In addition, iron and zinc have been shown to reduce tetracycline absorption [118], Figure 17 illustrates several of these interactions. These cations react with tetracycline to form a water-in-soluble and nonabsorbable complex. Obviously, these offending materials should not be co-administered with tetracycline antibiotics. 

For anabolic reactions, which result in the production of new cells, it is important to know the approximate chemical composition of the biomass. The bacterial protoplasm comprises 75 to 80% water. The solid material is composed of several complex organic molecules, such as proteins, carbohydrates, and DNA. The mean composition of these molecules can be approximated by a relatively simple empirical formula, C60H87O23N12P, or in an even more simple form as C5H7O2N10.Numerous other elements such as sulfur, sodium, potassium, calcium, magnesium,... 

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