Iodine biological significance

Even though the Mossbauer effect has been observed for almost 50 different elements and ca. 100 different nuclides, only a few of these elements are widely used as Mossbauer effect probes. The nuclides which are both experimentally viable and yield useful chemical information are iron-57, tin-119, antimony-121, and europium-151. More difficult to use but of importance in coordination chemistry are gold-197, nickel-61, ruthenium-99, tellurium-125, iodine-129, dysprosium-161, tungsten-182, and neptunium-237. Among these isotopes, iron-57 is by far the easiest, most informative, and most widely used nuclide in both traditional coordination chemistry and in studies of biologically significant coordination complexes. 

Biological significance of °I, 31 Blocking by iodine, 33 Effects in rats, 33 Specific activity, 31 Uptake equation, 32... 

Recently, a well-known trivalent iodine reagent, DIB with low toxicity and high stability was used in the synthesis of substituted pyrroles. The multi-component reaction (MCR) of primary amines 28, nitrostyrenes 29 and acetylac-etone 27 was smoothly performed in the presence of DIB to form substituted pyrroles 30 in good yields. This facile and simple DIB-mediat MCR is applicable for the synthesis of biologically significant tolmetin 31 and related pyrroles (Scheme 2) [18]. 

In summary, we have demonstrated the successful operation of a "Permasep" RO pleint on biologically active feed waters by using the intermittent injection of iodine as a bacterial control measure. The use of this shock procedure allowed for steady, continuous performcince of the plant euid is expected to have significant impact on future applications of PA membranes to biological action as well as waste waters. 

Because of the clinical significance of vitamin C, it is essential to In-able to detect and quantify its presence in various biological materials. Ana lytical methods have been developed to determine the amount of ascorbic acid in foods and in biological fluids such as blood and urine. Ascorbic acid may be assayed by titration with iodine, reaction with 2,4-dinitrophenylhy-drazine, or titration with a redox indicator, 2,6-dichlorophenolindophenol (DCIP) in acid solution. The latter method will be used in this experiment because it is reasonably accurate, rapid, and convenient and can be applied to many different types of samples. 

Nucleic acids can be labeled with a radioactive isotope in vitro by heating them in a mixture containing radioactive iodine and thallic trichloride (TICI3). The reaction is rapid and simple. It results in the formation of a stable covalent bond between the radioactive iodine atom and carbon atom 5 of cytosine in the nucleic acid. The biological properties of the nucleic acid are not significantly affected by this procedure. 

Although the most common label is still the radioactive hydrogen or iodine atom, the problems associated with radioactivity have led to a continual search for other techniques that may be in some ways preferable to it. Fluorescence, in principal, can be detected with the same sensitivity as radioactivity however, unlike radioactivity, there is a very significant natural background fluorescence in biological material. A variety of procedures have been called on to get around this problem (15), and some of these have made their way into commercial instrumentation. 

The generic term thyroid hormones refers to the iodinated amino acid derivatives T3 (3,3, 5-triiodo-L-thyronine) and T4 (3,3, 5,5 -tetraiodo-L-thyronine), the only iodinated hormones produced endogenously. T3 is the biologically active hormone and is, for the most part, produced from T4 in extrathyroidal tissues. T4 lacks significant bioactivity and is a hormone precursor however,... 

Very high bromide intake in the animal (>160 mg bro-mide/day) significantly shortens the biological half fife of iodine in the thyroid (from about 100 to 30 h). 

The introduction of one iodine atom does not significantly alter the biological properties of the molecule. With a larger amount of substimtion, the protein loses its properties and is generally quickly eliminated, due to its antigenic properties. 

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