Magnesium biological controls

Calcium, in contrast to magnesium, does not have an important function as an enzyme activator, in accord with its different distribution. It is very important, however, in the control and triggering of biological processes such as muscle contraction and the release of various chemicals, including hormones, defence chemicals and neurotransmitters. This occurs when, in response to some stimulus, the normal selectivity of the cell membrane or the membranes of internal organelles breaks down, and calcium ions are allowed to enter the cell. These bind to specific sites and trigger certain reactions. 

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. 

Once again, the level of the cations is controlled by membrane processes and metabolism from bacteria to animals and plants so that the same dependences on cations are found in all forms of life. For example, intracellular control of glycolysis is partly through the magnesium and potassium concentrations. Here we observe, much as has been seen in the chemistry of zinc, iron, cobalt, and copper, that biology has few variants on particular systems but these systems are chosen with remarkable ingenuity. 

Effective controls are omissions of ribosomes, template, nucleoside triphosphates, amino acids and magnesium. Omissions of protein fraction, tRNA and of monovalent ions also inhibit to some extent. Enzyme synthesis depends of course on incubation at biological temperatures. The final yields of enzymes were equal within the temperature range of 28° to 37°, but were progressively less at temperatures below 28°. The speed of synthesis, of course, varies with temperature. Other controls are addition of templates which do not carry the information for the protein to be tested, and the use of various antibiotics. 

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