Adenosine diphosphate, function

Adenosine triphosphate, coupled reactions and. 1128-1129 function of, 157, 1127-1128 reaction with glucose, 1129 structure of, 157, 1044 S-Adenosylmethionine, from methionine, 669 function of, 382-383 stereochemistry of, 315 structure of, 1045 Adipic acid, structure of, 753 ADP, sec Adenosine diphosphate Adrenaline, biosynthesis of, 382-383 molecular model of, 323 slructure of, 24... 

For ATP to carry out this function, it has to be produced from adenosine diphosphate (ADP) in an endergonic reaction that must be driven by another exergonic metabolic reaction. One exergonic reaction step that occurs in the overall oxidation of glucose in the cell is the oxidation of 3-phosphoglyceraldehyde to 3-phosphoglycerate by pyruvate, for which AG = —29,300 Jmol ... 

The main function of mitochondria is the generation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate, which is achieved by energy transfer from oxidation of fuels. Some cells (e.g. hepatocytes) contain several thousand mitochondria, whereas others, such as erythrocytes, lack them entirely. 

The section of the molecule discussed so far represents a functional unit. In the cell, it is produced from pantothenate. The molecule also occurs in a protein-bound form as 4 -phosphopantetheine in the enzyme fatty acid synthase (see p. 168). In coenzyme A, however, it is bound to 3, 5 -adenosine diphosphate. 

Fig. 1. The function of protein kinases [ADP (4), adenosine diphosphate ATP (3), adenosine triphosphate].

Abbreviations AD. adenosine diphosphate CPA. cone and platelet analyzer PCI, percutaneous coronary inten/entions PFA. platelet function analyzer TEG, thrombelastography. 

To demonstrate polymerase activity in a model cell, Chakrabarti et al. [79] encapsulated polynucleotide phosphorylase in vesicles composed of dimyris-toylphosphatidylcholine (DMPC). This enzyme can produce RNA from nucleoside diphosphates such as adenosine diphosphate (ADP) and does not require a template, so it has proven useful for initial studies of encapsulated polymerase activity (Fig. 10a). Furthermore, DMPC liposomes are sufficiently permeable so that 5-10 ADP molecules per second enter each vesicle. Under these conditions, measurable amounts of RNA in the form of polyadenylic acid were synthesized and accumulated in the vesicles after several days incubation. The enzyme-catalyzed reaction could be carried out in the presence of a protease external to the membrane, demonstrating that the vesicle membrane protected the encapsulated enzyme from hydrolytic degradation. Similar behavior has been observed with monocarboxylic acid vesicles [80], and it follows that complex phospholipids are not required for an encapsulated polymerase system to function. 

At the time I was in graduate school, it was recognized that living cells capture energy from oxidation of foodstuffs by making adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate. The ATP is then used in a myriad of functions — muscle contraction, nerve, brain, and kidney function, metabolic syntheses, and solute transport. How this oxidative phosphorylation occurrs remained for many years a major unsolved problem in biochemistry. 

Zucker MB, Peterson J.bihibiticm of adenosine diphosphate-mduced secondary aggregation and odier platelet functions by acetylsalricylic arid ingestkm. Proc Soc. Exp Biol Med 1968,127 547-551... 

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