Elements biological function

Table 19.3 (Continued) number Element Biological functions Toxicity" Comments...

Element Biological Function Phytotoxicity Mammalian Toxicity... 

RNA structures, compared to the helical motifs that dominate DNA, are quite diverse, assuming various loop conformations in addition to helical structures. This diversity allows RNA molecules to assume a wide variety of tertiary structures with many biological functions beyond the storage and propagation of the genetic code. Examples include transfer RNA, which is involved in the translation of mRNA into proteins, the RNA components of ribosomes, the translation machinery, and catalytic RNA molecules. In addition, it is now known that secondary and tertiary elements of mRNA can act to regulate the translation of its own primary sequence. Such diversity makes RNA a prime area for the study of structure-function relationships to which computational approaches can make a significant contribution. 

Simple combinations of a few secondary strucfure elements with a specific geometric arrangement have been found to occur frequently in protein structures. These units have been called either supersecondary structures or motifs. We will use the term "motif" throughout this book. Some of these motifs can be associated with a particular function such as DNA binding others have no specific biological function alone but are part of larger strucfural and functional assemblies. 

Trace elements found in the human body serving essential biological functions include Mn,... 

Mutations that stimulate exon 10 inclusion into the human tau mRNA, which is regulated by an intricate interplay of cis elements and trans factors, cause FTDP-17 and other tauopathies. This suggests that the ratio of exon 10 inclusion to exclusion in the adult brain is one of the factors to determine biological functions of the tau protein. 

Table I9.3 lists elements that have been found to be essentia] or poisonous, together with notes on biological functions and leading references that may be followed by the interested reader.118 It is certain that the information In this list wifi be expanded as the present techniques and theory are improved.

Researchers J, Versieck and L. Vanballenberghe (University Hospital, Ghent. Belgium) have observed, Tin has chemical properties offering potentials for a biological function, The element has a tendency to form truly covalent linkages as well as coordination complexes hence, it was hypothesized that it could well contribute to the tertiary structure of proteins or other biologically important macromolcculcs, such as nucleic acids. 

Understanding the biological functions of S100 proteins will crucially depend on the identification of their target proteins. During the last decade, a large number of possible interactors have been described involving enzymes, cytoskeletal elements as well as transcription factors. 

Fig. 2. Periodic table indicating relative abundance and biological importance of elements. Highlighted elements are the 30 most abundant crustal elements with concentrations ranging from 46 % for oxygen to 0.1 yg/g for selenium. Bold faced elements have known biological functions with indicating limited data and controversy. Data taken from Wood and Wang, 1983.

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