Role in Biology

All the long-range forces discussed in this chapter play a role in biological processes. Interactions between membranes, proteins, ligands, antibodies... 

Some esters of inorganic acids, such as dimethyl sulfate, are used as reagents in synthetic organic chemistry. Certain naturally occuning alkyl phosphates play an important role in biological processes. 

We shall encounter other biological processes in which the NAD"" conversion plays a prominent role in biological oxidation-reduction. 

Up to this point all our attention has been directed toward aldoses, carbohydrates having an aldehyde function in their open-chain form. Aldoses are more common than ketoses, and their- role in biological processes has been more thoroughly studied. Nevertheless, a large number of ketoses are known, and several of them are pivotal intermediates in carbohydrate biosynthesis and metabolism. Examples of some ketoses include D-ribulose, L-xylulose, and /-fructose ... 

H. SiGEL and A. Sigel (eds). Metal Ions in Biological Systems, Vol. 24, Aluminium and its Role in Biology, Marcel Dekker, New York, 1988, 440 pp. 

In as far as other analytical methods are concerned, many specific reactions have been elaborated for the quantitative determination of 2-deoxy aldoses. 2-Deoxy-D-ribose (2-deoxy-D-erythro-pentose), a compound which was recognized early as playing an important role in biological systems, has been of particular interest. Overend and Stacey (43) have given a critical review of the methods available until 1952 for the estimation of 2-deoxy pentoses. A recent summary of specific methods for the identification and quantitative estimation of the different classes of deoxy sugars has been prepared by Dische (13). 

Hydrogen bonds play an important part in determining such properties as solubility, melting points, and boiling points, and in affecting the form and stability of crystal structures. They play a crucial role in biological systems. For ex-... 

Despite Lavoisier s early work on the link between energy and life, calorimetric measurements played a relatively minor role in biology until recent years, primarily because of practical obstacles. Every organism must take in and give off matter as part of its normal function, and it is very difficult to make accurate heat-flow measurements when matter is transferred. Moreover, the sizes of many organisms are poorly matched to the sizes of calorimeters. Although a chemist can adjust the amount of a substance on which to carry out calorimetry, a biologist often cannot. 

Liquid crystal sounds like a contradiction. Liquids are fluid, their molecules continually changing places in a manner that is not particularly well organized. Crystals are immobile, their molecules locked into fixed positions that form regular patterns. Yet, not only does this unusual combination of fluidity and regular patterns exist, it plays important roles in biological organisms. 

Osmotic pressure plays an important role in biological chemistry because the cells of the human body are encased in semipermeable membranes and bathed in body fluids. Under normal physiological conditions, the body fluid outside the cells has the same total solute molarity as the fluid inside the cells, and there is no net osmosis across cell membranes. Solutions with the same solute molarity are called isotonic solutions. 

The compounds that are identifiable in the sea represent a vast array of biochemicals attributable to the life and death of marine plants and animals. They are generally grouped into six classes based on structural similarities hydrocarbons, carbohydrates, lipids, fatty acids, amino acids, and nucleic acids. Because they represent compounds that can be quantified and understood for their chemical properties and known role in biological systems, a great deal of information has been accumulated over the years about these groups and the specific compounds found within them.7... 

As in the case of esters, hydrolysis of amides is also a fundamental reaction in organic chemistry and plays a key role in biological systems. The reaction has been covered extensively in organic chemistry and biochemistry textbooks. 

Copper-olefin bonding is of both practical and theoretical interest in view of the catalytic activity of copper(I) toward olefin activation and its role in biological systems. 

Radicals and Excited States and Their Potential Role in Biological Systems... 

Methyl transferases are responsible for methylation of a nucleophile, typically using SAM as the carbon donor. They are known to accept a wide range of nucleophiles such as halides (eq. 1 in Figure 13.22) [64], amines (eq. 2 in Figure 13.22) [65], hydroxyls, and enolates. As expected, the reactivity of methyl transfer to halides follows the order of iodide, bromide, and chloride, with chloride being the poorest acceptor. Methylation of amines in nucleotides and proteins plays important roles in biological activities. 

Nevertheless, even with these caveats it is likely that mRNA microarray technology will play an increasing role in biological science. The technology... 

Table 1 Relative abundance and examples of functions of inorganic elements (and a few selected non-metals) that play an important role in biology. Adapted extensively from Mason and Moore, 1982.

Several metal ions play a crucial role in biological processes, whereas some others are toxic. Alteration of the metal concentration in the body can often be correlated to disease states. The necessity for in vivo determination of metal ion concentration and distribution has prompted research to develop appropriate metal-responsive MRI contrast agents. 

The ORAC assay proposed by Ou and others (2001) is limited to hydrophilic antioxidants because of the aqueous environment of the assay. However, lipophilic antioxidants play a critical role in biological defense systems. Huang and others (2002) expanded the assay to the lipidic fraction by introducing a randomly methylated 13-cyclodextrin (RMCD) as a water-solubility enhancer for lipophilic antioxidants. Various kinds of foods, including fruit juices and drinks, fruits, vegetables, nuts, and dried fruits, have been evaluated with this method (Zhou and Yu 2006 Wu and others 2004 Kevers and others 2007 Wang and Ballington 2007 Almeida and others 2008 Mullen and others 2007). 

There has been great interest in Cu(II) as a result of its role in biology, and the versatility in its available radioactive isotopes. The chemistry of bis(thiosemicarbazonato) metal complexes has received much interest over the last decade with particular interest in the copper complexes that are known blood perfusion tracers and also display hypoxic selectivity. Biomedical applications revolve around its redox chemistry (12,83-88,98-104). 

The hydrated cation Ca2+aq is of prime importance to the aqueous solution chemistry of calcium, and to most of its various roles in biological systems. The relation between lattice energy and hydration energies of the constituent ions determine solubilities, the size of the hydrated cation controls selectivity and the passage of ions through channels, and the work required to remove some or all of the water of hydration is relevant both to... 

Table XI (346-390) lists a number of calcium-binding proteins and indicates very succinctly their role in biological systems. This table both illustrates the range of functions of calcium-binding proteins and serves to introduce those which appear subsequently in this chapter. The structures and functions of particularly important calcium-binding proteins such as calmodulin, parvalbumin, and troponin C are described in standard texts on biochemistry. The minimal Table XI entry for the particularly important calmodulins is amplified in the next paragraph. Table XI provides a sprinkling of references to enable readers to gain entry into the literature, for these and for most of the less-familiar species.

Carafoli, E. Inesi, G. Rosen, B. P. In Metal Ions in Biological Systems. Volume 17. Calcium and its Role in BiologyEd. Sigel, H. Marcel Dekker New York, 1984, pp. 129-186. 

Dienes and polyenes have been a subject of great interest due to their important role in biology, materials science and organic synthesis. The mechanism of vision involves cis-trans photoisomerization of 11 -civ-retinal, an aldehyde formed from a linear polyene. Moreover, this kind of molecule exhibits high linear and non-linear electrical and optical properties. Short polyenes are also involved in pericyclic reactions, one of the most important classes of organic reactions. 

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