Iron, Copper and Molybdenum

The redox system of Fe /Fe covers a wide range of potentials (Table 2.5) depending on the attached ligands. Therefore, the system is exceptionally suitable for bridging large potential differences in a stepwise electron transport system. Such an example is encountered in the transfer of electrons by the cytochromes as members of the respiratory chain (cf. textbook of biochemistry) or in the biosynthesis of unsaturated fatty acids (cf. 3.2.4), and by some individual enzymes. 

Iron-containing enzymes are attributed either to the heme (examples in 3.3.2.2) or to the nonheme Fe-containing proteins. The latter case is exemplified by lipoxygenase, for which the mechanism of activity is illustrated in section 3.7.2.2, or by xanthine oxidase. 

Xanthine oxidase from milk (Mr = 275,000) reacts with many electron donors and acceptors. However, this enzyme is most active with substrates such as xanthine or hypoxanthine as electron donors and molecular oxygen as the electron acceptor. The enzyme is assumed to have two active sites per molecule, with each having 1 FAD moiety, 4 Fe-atoms and 1 Mo-atom. During the oxidation of xanthine to uric acid  

Under certain conditions the enzyme releases a portion of the oxygen when only one electron transfer has been completed. This yields Of, the superoxide radical anion, with one unpaired electron. This ion can initiate lipid peroxidation by a chain reaction (cf. 3.7.2.1.8). 

Polyphenol oxidases and ascorbic acid oxidase, which occur in food, are known to have a Cu /Cu redox system as a prosthetic group. Polyphenol oxidases play an important role in the quality of food of plant origin because they cause the enzymatic browning for example in potatoes, apples and mushrooms. Tyrosinases, catecholases, phenolases or cresolases are enzymes that react with oxygen and a large range of mono and diphenols. 

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Rao, T.A. 1984. Iron, copper and molybdenum in the different body parts of some clupeoids. Indian Jour. 

It facilitates better uptake of nutrients like P and immobile trace elements like Zinc, Cobalt, Manganese, Iron, Copper, and Molybdenum leading to better nutrients for the plants. 

Dan] Datmoehl, W., The Alloys of Iron, Copper and Molybdenum (in German), Mss. Vero. ... 

Discussion. Molybdates [Mo(VI)] are quantitatively reduced in 2M hydrochloric acid solution at 60-80 °C by the silver reductor to Mo(V). The reduced molybdenum solution is sufficiently stable over short periods of time in air to be titrated with standard cerium(IV) sulphate solution using ferroin or /V-phenylanthranilic acid as indicator. Nitric acid must be completely absent the presence of a little phosphoric(V) acid during the reduction of the molybdenum(VI) is not harmful and, indeed, appears to increase the rapidity of the subsequent oxidation with cerium(IV) sulphate. Elements such as iron, copper, and vanadium interfere nitrate interferes, since its reduction is catalysed by the presence of molybdates. 

Soil pH is easily tested for and determines the availability of nutrients and the success of white clover. Very acid soils (below pH 5.0) will cause a deficiency of the trace elements iron, boron, copper and molybdenum and conversely will cause injury to plant growth by increasing the availability of aluminium and manganese to toxic levels. Over-liming, on the other hand, which can raise the pH above 6.5, will reduce the availability of certain essential elements such as phosphorus, manganese and boron. 

Sec also Chelates and Chelation Cobalt Copper Gold Hydrate Iron Manganese and Molybdenum (In Biological Systems). 

For suspension cultures, the concentration of calcium and magnesium should be kept low to prevent cell aggregation and adhesion. Other metals, such as iron, manganese, selenium, vanadium, zinc, copper, and molybdenum, are usually added to the culture medium, but at reduced concentrations, and mainly if the medium is not supplemented with animal serum. 

Although neither element is very abundant in the earth s crust, molybdenum in particular has a concentration in natural waters that is greater than those of other biologically important elements such as iron, copper, and zinc. 

Finally before discussing each metal in detail, it is necessary to mention the question of measurement temperature. Transition metals often have very fast relaxation times and, whilst copper and molybdenum can in most cases be studied at room temperature, some haemoproteins and many iron-sulphur proteins have to be cooled to close to liquid helium temperatures (4.2°K) for reasonable spectra to be obtained. This means that the nearest we can get to the biological steady state may be by rapidly freezing our samples and that kinetic measurements will also have to involve rapid freeze techniques. Apparatus to do this has been developed but resolution is at present limited to about 5 msec. Since we are studying properties of d electrons, ESR information is in many ways complementary to data obtained from UV/visible spectra where electronic excita-... 

The catalysts which were found to lie effective in the formation of methane from hydrogen and cavlion monoxide with the greatest activity were composed of nickel, iron, cobalt, and molybdenum. The catalysts most active in methanol synthesis in general consists of the oxides or mixtures of the oxides of zinc, copper, or chromium. Iron promoted with alkali lias been found to be very active but not at all directive in the synthesis of aliphatic compounds from water-gas. With it only a very complex mixture results, which it is impossible to separate commercially into constituents. 

The greatest decreases were found in iodine (down to 17%), iron (30%) and molybdenum (47%), whereas the zinc, copper, nickel, and manganese contents were lowered to half the amount found at the end of April. The age of the plants has a significant influence on the macro and trace element contents of these elements, which are essential for flora and fauna. Generally, herbivorous wild animals eat foods rich in macro and trace elements in early spring. 

This book is a general survey of the nature of trace metals in petroleum and includes analytical methods for their determination. Vanadium, iron, nickel, cadmium, copper, and molybdenum— their nature, determination, chemical aspects, geochemistry, occurrence in new and used petroleum byproducts and their recovery for resource use—are dealt with in detail by the expert authors in this volume. Among the methods covered are instrumental analysis, neutron activation, activation analysis, oxidative demetallation and kinetic studies. Includes 54 figures and 60 tables. 

Hulagur, B. F., and Dangarwala, R. T. (1982). Effect of zinc, copper and phosphorus fertilization on the uptake of iron, manganese and molybdenum by hybrid maize. Madras Agric. J. 69 11-16. 

Mumetal /myoo-met-al/ [Trademark) A magnetic alloy containing about 75% nickel, the remainder being iron, copper, and chromium and sometimes molybdenum. It is easily magnetized and demagnetized, has a high permeability, and is used in transformer cores and electromechanical equipment. 

Many enzymes also show a specific requirement for a particular metal ion. These include various ions of iron, copper, cobalt, molybdenum, zinc, manganese, magnesium, calcium, and potassium. The metal ion is thought to have a binding function for the substrate, coenzyme, and enzyme. Thus, these metals are needed in the diet in trace amounts. 

METALLO ENZYMES AND METALLO COENZYMES — covers the preparation, analysis, and biochemical effects of enzymes and co-enzymes that contain metals such as cobalt, copper, iron, zinc, and molybdenum. Also included are items dealing with metallo proteins, metal-containing vitamins, and mechanisms by which metals are bound to various enzymes. 

Transition elements have some biological functions for chemistry of living systems. Metals, such as iron, cobalt, copper, and molybdenum have functions in living systems, whereas protein contains iron, which helps in electron transfer and oxygen transport. Most transition metal elements plays similar major roles in various biological living systems and for these reasons we focused on the transition metals. 

The use of iron-oxidizing autotrophs in the removal of pyrite from coal (Ashmead, 1955 Zarubina et al., 1959) and in the secondary recovery of copper and molybdenum from their sulfide minerals has already been reported (Bryner et al., 1954 Bryner and Anderson, 1957 Bryner and... 

Since a compound atom contains only i atom of one of the elements, and since the ratio of the oxygen in chromic oxide to that in chromic acid is i to 2, these compounds are Ch + 30 and Ch + 60. Although the corresponding molybdenum compounds are very like the chromium compounds they are M0 + 2O and Mo+ 30. The lower oxides of iron, copper and lead, and the oxides of silver, zinc, calcium, potassium and sodium have the formulae R + 2O. In neutral salts one formula weight of base is usually combined with two of acid. The formulae of compounds do not necessarily represent equal volumes. ... 

Micronutrients Elements that plants need in lesser amounts such as iron, chlorine, manganese, boron, zinc, copper, and molybdenum. 

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