Essential elements, in biological

Unlike the metals, the chemistry of these elements is diverse. Despite their relatively small number, most of the essential elements IN BIOLOGICAL SYSTEMS ARE NONMETALS (O, C, H, N, P, AND S). This group also includes the most unreactive elements—the... 

Of the 117 elements known, only 25 are nonmetallic elements. Unlike the metals, the chemistry of these elements is diverse. Despite their relatively small number, most of the essential elements in biological systems are nonmetals (H, C, N, P, O, S, Cl, and I). This group of nonmetallic elements also includes the most unreactive of the elements—the noble gases. The unique properties of hydrogen set it aside from the rest of the elements in the periodic table. A whole branch of chemistry—organic chemistry—is based on carbon compounds. 

The 1980 s and the early 1990 s have seen the blossoming development of the biotechnology field. Three-phase fluidized bed bioreactors have become an essential element in the commercialization of processes to yield products and treat wastewater via biological mechanisms. Fluidized bed bioreactors have been applied in the areas of wastewater treatment, discussed previously, fermentation, and cell culture. The large scale application of three-phase fluidized bed or slurry bubble column fermen-tors are represented by ethanol production in a 10,000 liter fermentor (Samejima et al., 1984), penicillin production in a 200 liter fermentor (Endo et al., 1986), and the production of monoclonal antibodies in a 1,000 liter slurry bubble column bioreactor (Birch et al., 1985). Fan (1989) provides a complete review of biological applications of three-phase fluidized beds up to 1989. Part II of this chapter covers the recent developments in three-phase fluidized bed bioreactor technology. 

While these reactions form an essential element in modem biochemistry and cell biology, the way they were established experimentally is seldom described. A knowledge of the limitations of the procedures available at the time when the reactions were discovered and of the conceptual contexts into which the new data had to be accommodated, may help biochemists to appreciate how their subject began and the radical changes there have been in the latter half of the twentieth century. 

It is impossible to cover adequately the chemistry of various elements in biological systems in a single chapter. Before discussing the salient points of other essential and trace elements, the biochemistry of iron will be discussed briefly. Iron is the most... 

Many of the non metals such as hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, chlorine, and iodine are essential elements, and most are used in quantities for beyond the trace levels. Nevertheless, most of the chemistry of these elements in biological systems is more closely associated with organic chemistry than with inorganic chemistry. 

Zinc is one of the more abundant trace elements (Table 1), and its essential role in biological processes is now well established. Over 100 enzymes require zinc for activity, even though only a relatively small number of these have been well studied. Examples are listed in Table 12. In this discussion most attention will be paid to the well-characterized zinc enzymes, but it must be stressed that there is increasing interest in other aspects of the biological chemistry of zinc, notably... 

These data may imply that cellular mechanisms for calcium transfer and homeostasis are intimately tied up with mitochondria and that biomineralization is an essential element in Ca2+-regulation processes481,482). For a review on the role of mitochondria in the deposition of amorphous calcium phosphate in the early steps of biological calcification, see473,474. ... 

The abundance and ratios of important elements in biological cycles (e.g., C, H, N, O, S, and P) provide the basic foundation of information on organic matter cycling. For example, concentrations of total organic carbon (TOC) provide the most important indicator of organic matter since approximately 50% of most organic matter consists of C. As discussed in chapter 8, TOC in estuaries is derived from a broad spectrum of sources with very different structural properties and decay rates. Consequently, while TOC provides essential information on spatial and temporal dynamics of organic matter it lacks any specificity to source or age of the material. 

Iron enjoys a unique position as an essential trace element in biological systems. By virtue of its role in electron transfer it is generally present in higher concentration than the other trace elements. At the same time its extreme insolubility at physiological pH and the myriad of reaction... 

Inductively Coupled Plasma Atomic Emission Spectrometry ICP-AES is a technique half-way between FAAS and ET-AAS in terms of detection power. Among all ICP-AES features its robustness against matrix effects and its ability to carry out multielemental analysis predominate as the most advantageous [76-80], Multielemental analysis has also been successfully used to establish reference values [6, 76, 81-84] for many major and trace essential elements in different matrices of biological and nutritional interest, particularly in milk samples [81-83], Reference values for minor and trace element in human milk are collected in Table 13.8. 

The early 1960 s saw the introduction of flame atomic absorption spectrometry (AAS) to clinical laboratories and this provided a sensitive yet simple analytical technique for the estimation of some trace elements in biological fluids. Trace elements is now perhaps an inaccurate description for those metals previously detectable in only small amounts when using older and less sensitive analytical techniques. Many such elements can now be estimated with precision and this has proved a great stimulus to trace-element research in clinical medicine. The number of trace elements known to be essential to man has doubled in the last twenty years [1]. Specific and treatable diseases are now known to be associated with excess or deficiency of trace elements and even in advanced societies dietary intake of some elements may be less than ideal [2]. Thus, monitoring of biological fluids for trace element levels in both health and disease can contribute towards major advances in nutritional management. 

Dybczynski, R. Considerations on the accuracy of determination of some essential and/or toxic elements in biological materials. Chem. Anal. (Warsaw) 47, 325-334 (2002)... 

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