Adenosine high energy phosphate bonds

An intriguing use of the oxidative potential stored in thianthrene radical ion(l-l-) is provided by the formation of high-energy phosphate bonds. Thus, the interaction of adenosine-5 -phosphate (AMP) and orthophos-phoric acid, each as their ammonium salts, with two equivalents of thi-... 

ATP Regarded as Store House of Energy Adenosine triphosphate (ATP) in a nucleotide consists of purine base adenine, a pentose sugar ribose and three molecules of phosphate. It contains two oxygen to phosphorus bonds between two phosphate units. These phosphorus bonds are called high energy phosphatic bonds. 

ADP (Adenosine Diphosphate) An important cellular metabolite involved with energy exchange within the cell. Chemical energy is conserved in a cell by the phosphorylation of ADP to ATP primarily in the mitochondria, as a high energy phosphate bond. ADP combined with CP forms ATP, the usable fuel for muscular contractions. 

Adenosine triphosphate (ATP) is the primary energy source for ceU-free synthesis reactions. Rapid depletion of ATP leads to the cessation of translation in under an hour in batch mode. ATP regeneration systems are used to extend the life of translation reactions by maintaining a stable ATP concentration. ATP is regenerated by the enzyme-catalyzed transfer of high-energy phosphate bonds from a secondary energy... 

Energy from fuel oxidation is converted to the high-energy phosphate bonds of adenosine triphosphate (ATP) by the process of oxidative phosphorylation. Most of the energy from oxidation of fuels in the TCA cycle and other pathways is conserved in the form of the reduced electron-accepting coenzymes, NADH and FAD(2H). The electron transport chain oxidizes NADH and FAD(2H), and donates the electrons to O2, which is reduced to H2O (Fig. 21.1). Energy from reduction 0/O2 is used for phosphorylation of adenosine diphosphate (ADP) to ATP by ATP synthase (FgFjATPase). The net yield of oxidative phosphorylation is approximately 2.5 moles of ATP per mole of NADH oxidized, or 1.5 moles of ATP per mole of FAD(2H) oxidized. 

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... 

The ADP in the above reaction indicates adenosine diphosphate, which has the same structure as ATP but which has one less terminal phosphate group. By an entirely different procedure, Strehler (34) has been able to show that the ATP content of illuminated Chlorella is markedly increased following an anaerobic period in the dark. There seems to be little doubt that the production of high-energy phosphate bonds is connected to the photochemical phase of photosynthesis, but the mechanism of the reactions involved is not well understood at the present time. 

P = high energy phosphate bond PAL = phenylalanine ammonia lyase PAPS = 3 -adenosine-5 -phosphosulphate Pi = inorganic orthophosphate PPi = inorganic pyrophosphate PEP = phosphoenolpyruvate... 

The adenosine triphosphate (ATP) molecule is essential for life. It provides energy for muscle contraction, nerve conduction, many biochemical reactions, etc. At rest ATP turnover is 28 g (1 oz) of ATP per minute which is equivalent to 1.4kg (3 lb) per hour. During strenuous exercise, ATP turnover increases to a massive O.Skg/min Figure 10.1 shows that ATP consists of adenine, ribose and three phosphate groups that are identified as a-, P- and y-. Hydrolysis of the high energy phosphoanhydride bonds between the P- and y-phosphorus atoms, or alternatively, between the a- and P-phosphorus atoms releases energy for the biochemical reactions of life. 

The following abbreviations will be used in this article. ATP = adenosine triphosphate ADP — adenosine diphosphate DPNox oxidized diphosphopyri-dine nucleotide DPNred = reduced diphosphopyridine nucleotide CoA or CoA—SH = coenzyme A CoA—S—COCH3 = acetyl-coenzyme A FAD = flavin adenine dinucleotide R—P = low-energy phosphate bond R P = high-energy bond Pi = inorganic orthophosphate. 

The molecule of ATP therefore contains two phosphate bonds which are energy-rich and one which is relatively poor in energy. We use the symbol P to represent a high energy phosphate radical so that the ATP molecule can be represented A-P P P where A represents the nucleoside, adenosine. 

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