Biological importance of iron

In Aphorisms, Hippocrates asserted that diseases which are not healed by cures, are healed by iron . We know now that iron is distributed in all of the living organisms and that all of the cells need iron to survive and to grow. For this reason. Nature has coined the transferrins of which the mission is to furnish this invaluable metal to all living cells (for a review, see ref. [7]). 

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In this chapter we describe selected aspects of the biological chemistry of iron, with particular reference to iron-containing enzymes. It would be difficult to underestimate the biological importance of iron for almost all... 

Such a large interest in this field is primarily caused by the biological importance of iron porphyrin complexes as oxygen carriers in hemoglobin and... 

Chapter 7 has reported on the importance of iron in biological species. Because iron is the most abundant transition metal found in biological species, one would expect a wide variety of iron-containing proteins and metalloenzymes. Only a few of these have been treated in any detail in this chapter. Little or no mention has been made of how or why iron ions evolved to be the most biologically abundant transition metal ions probably their usefulness in redox situations and for electron transport has something to do with their popularity. Iron homeostasis in biological species has not been discussed, although this... 

In the preceding section we saw the importance of iron in biological systems. Of course, iron is also very important in many other ways in our world. In this section we will discuss the isolation of metals from their natural sources and the formulation of metals into useful materials, with special emphasis on the role of iron. 

As soon as the first N2 complex was reported, many workers began looking for compounds of iron and molybdenum because of the biological importance of these metals. Compounds of iron were soon prepared, but it was not until this year that the first molybdenum-N2 compounds were found. Misono et al. have reported (25) the composition of the molybdenum complex mentioned earlier, together with the preparation of a second complex containing two molecules of N2. 

An important biological requirement of iron-enterobactin systems is the release of iron from the highly stable [Fe(ent)] complex once inside the cell. The redox potential for [Fe(ent)j] (estimated as ca. — 750 mV at pH 7) is probably too negative to allow reduction to Fe" by known biological reductants at physiological pH. At lower pH the redox potential may shift towards positive values, however. In one mechanism for the release of iron from enterobactin at low pH it is proposed that an internal redox reaction occurs between Fe " and catechol to generate a blue Fc"-semiquin-... 

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