Magnesium ions biology

The natural fluorescence of CTC and its derivatives has been used extensively to determine small amounts of CTC in biological materials. Kohn (86) showed that the fluorescent complex formed by CTC with calcium ions and barbital could be extracted from animal tissues into an organic solvent and then measured spectrofluorometrically. The intense fluorescence of anhydro-CTC was used by Hayes and DuBuy (87) to determine CTC in animal tissues, tissue culture cells, and bacteria. Poiger and Schlatter (88) extracted CTC from biological material into ethyl acetate as the CTC-calcium trichloroacetate ion pair. The fluorescence of the antibiotic was then enhanced by the addition of magnesium ions and a base. 

Magnesium ions are also involved in biological processes and occur in cells at millimolar concentrations [315]. Magnesium can be estimated based on the chemical shift difference of the resonances of adenosine triphosphate (ATP) using P NMR [316-318], though P NMR has intrinsically low signal-to-noise, exacerbated under many pathophysiological conditions, such as ischemia. 

Primer Activity. Biologically active DNA will replicate itself in vitro if supplied with an enzyme, DNA polymerase, the triphosphates of adenosine, guanosine, cytidine, and thymidine, magnesium ion and the proper conditions of temperature and pH. The same DNA (or other samples of biologically active DNA) if supplied with another enzyme,... 

Siccl. H. and A. Sigcl Metal tanr in Biological Svstcnts Compendium on Magnesium ion I tts Roll in Biology. Nutrition, and Li /V iotogw Marcel Dckkcr. Inc.. New York. NY. 1190... 

Reactions involving the formation and hydrolysis of phosphate and polyphosphate esters are of vital importance in biological systems in which it is found that magnesium ions are almost invariably implicated. The formation and decomposition of adenosine triphosphate are the fundamental reactions involved in energy storage in living systems. In this context, it is perhaps relevant to note that the hydrolysis of ATP is enhanced, albeit in a very modest manner, by some cobalt(m) complexes. 

A completely different example of cofactor generation in a microsystem is the local production of magnesium ions to control the position of activation of a DNA restriction enzyme (Katsura et al., 2004). Alternative DNA restriction schemes are important to cut DNA at specific positions, different from the conventional molecular biological methods. Control of restriction was achieved by applying a direct current to a needle electrode of magnesium. Only when and where the magnesium ions from this needle were produced, the restriction enzyme became activated. 

Much structural biology analysis has been performed on protein kinase A (PKA), and its catalytic residues are conserved across the family (6, 7). In PKA, lysine 72 and glutamate 91 orient the y-phosphate toward the protein substrate (Fig. 2b). Aspartate 166 acts as a catalytic base to accept the proton from the hydroxyl nucleophile, and Lys 168 acts as an electrostatic catalyst to stabilize the y-phosphate during the reaction. Asparagine 171 positions a magnesium ion that coordinates the a/fi phosphates (Fig. 2b). 

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