Adenosine triphosphate , bond function

F. H. Westheimer (1987) has provided a detailed survey of the multifarious ways in which phosphorus derivatives function in living systems (Table 4.7). The particular importance of phosphorus becomes clear when we remember that the daily turnover of adenosine triphosphate (ATP) in the metabolic processes of each human being amounts to several kilograms Phosphate residues bond two nucleotides or deoxynucleotides in the form of a diester, thus making possible the formation of RNA and DNA the phosphate always contains an ionic moiety, the negative charge of which stabilizes the diester towards hydrolysis and prevents transfer of these molecules across the lipid membrane. 

An alcohol can react with phosphoric acid to produce a phosphate ester iphosphoester). When two phosphate groups are joined, the resulting bond is a phosphoric anhydride bond. These two functional groups are important to the structure and fimction o( adenosine triphosphate (ATP), the universal energy currency of all cells. Cellular enzymes can carry out a reaction between a thiol and a carboxylic acid to produce a thioester. This reaction is essential for the activation of acyl groups in carbohydrate and fatty acid metabolism. Coenz)une A is the most important thiol involved in these pathways. 

The first two compounds have particularly important bio functions in connection with energy storage. Creatine phosphate was first isolated by Eggleton [13] from frog muscle in 1927. The concept of high-energy phosphate bonds was introduced in 1941 by Lipmann [8], who postulated that adenosine triphosphate (ATP) (11.10a) functioned in a cyclic manner as the energy carrier in the numerous... 

Mitchell/ Peter Dennis (1920-92) English biochemist who revolutionized thought on the process of oxidative phosphorylation in which adenosine triphosphate (ATP) is regenerated from adenosine diphosphate (ADP) and phosphate. Breakdown of ATP to ADP releases large amounts of energy for cell functions from the phosphate bonds. MitcheU proposed that electron transport formed a proton gradient across the mitochondrial membrane that directly brought about the synthesis of ATP from ADP. He was awarded the 1978 Nobel Prize in chemistry. 

Adenosine triphosphate (ATP) is sometimes called the universal energy carrier or molecular eneigy currency. It contains two high-eneigy bonds (shown in red) that, when hydrolyzed (broken by the addition of water), release the energy necessary for cell function. Resonance stabilization of the hydrogen phosphate ion is one of the reasons the breakdown of ATP releases energy. 

Chemical reactions between biochemical compounds are enhanced by biological catalysts called enzymes, which consist mostly or entirely of globular proteins. In many cases a cofactor is needed to combine with an otherwise inactive protein to produce the catalytically active enzyme complex. The two distinct varieties of cofactors are coenzymes, which are complex organic molecules, and metal ions. Enzymes catalyze six major classes of reactions 1) Oxidoreductases (oxidation-reduction reactions), 2) Transferases (transfer of functional groups), 3) Hydrolases (hydrolysis reactions), 4) Lyases (addition to double bonds, 5) Isomerases (isomerization reactions) and 6) Ligases (formation of bonds with ATP (adenosine triphosphate) cleavage) [1]. 

The principal function of the oxidation of carbohydrates and fatty acids is to make available to the cells the free energy released in the oxidation process, in a form physiologically usable for cellular energy processes, viz, ATP. This is accomplished by the process known as oxidative phosphorylation, whereby adenosine triphosphate (ATP) with three phosphate groups, two of which are held by high energy bonds, is formed from adenosine diphosphate (ADP) by the addition of phosphate. 

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