Adenosine diphosphate phosphorylation

A good example of an affinity label for creatine kinase has been presented (35). This enzyme catalyzes the reversible transfer of a phosphoryl group from adenosine triphosphate [56-65-5] (17) to creatine [57-00-1] (18), leading to adenosine diphosphate [7584-99-8] (19) and phosphocreatine [67-07-2]... 

A remarkable feature of the bioenergetic oxidation reactions of nutrients in cells is the fact that they are always coupled to another reaction, that of synthesis of the energy-rich chemical substance adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (oxidative phosphorylation Engelgardt and Ljubimova, 1939) ... 

In the preceding sections the conversion of purines and purine nucleosides to purine nucleoside monophosphates has been discussed. The monophosphates of adenosine and guanosine must be converted to their di- and triphosphates for polymerization to RNA, for reduction to 2 -deoxyribonucleoside diphosphates, and for the many other reactions in which they take part. Adenosine triphosphate is produced by oxidative phosphorylation and by transfer of phosphate from 1,3-diphosphoglycerate and phosphopyruvate to adenosine diphosphate. A series of transphosphorylations distributes phosphate from adenosine triphosphate to all of the other nucleotides. Two classes of enzymes, termed nucleoside mono-phosphokinases and nucleoside diphosphokinases, catalyse the formation of the nucleoside di- and triphosphates by the transfer of the terminal phosphoryl group from adenosine triphosphate. Muscle adenylate kinase (myokinase)... 

Within cells, the hydrolysis of ATP strips off a phosphoryl group from ATP to produce adenosine diphosphate (ADP) ATP +H20 < ADP + HP04... 

In another important class of regulatory enzymes, activity is modulated by covalent modification of the enzyme molecule. Modifying groups include phosphoryl, adenylyl, uridylyl, methyl, and adenosine diphosphate ribosyl groups (Fig. 6-30). These groups are generally linked to and removed from the regulatory enzyme by separate enzymes. 

The problem of oxidative phosphorylation has been approached through model studies that utilize the phosphorylating potential of metaphosphate. In the mitrochondrial process inorganic phosphate and adenosine diphosphate are converted to adenosine triphosphate. Wieland, in a series of papers (e.g. ref. 31), has shown that a variety of thiolactones can activate inorganic phosphate in the presence of bromine for transfer to adenosine diphosphate (ADP). The intermediate may be an acyl phosphate or a sulfonium salt similar to that postulated by Higuchi and Gensch32 and by Lambeth and Lardy33, viz. 

The biological roles of phosphorus include (1) anabolic and catabolic reactions, as exemplified by its essentiality in high-energy bond formation, e.g., ATP (adenosine triphosphate), ADP (adenosine diphosphate), etc., and the formation of phosphorylated intermediates in carbohydrate metabolism ... 

PHOS PHORYLATI ON (Pliotosy lithe tic). Photosy nthe tic conversion of light energy into the potential energy of chemical bonds involves an electron transport chain, and the phosphorylation of ADP (adenosine diphosphate)... 

The oxygen formed clearly comes from H20 and not from C02, because photosynthesis in the presence of water labeled with lgO produces oxygen labeled with 180, whereas carbon dioxide labeled with 180 does not give oxygen labeled with 180. Notice that the oxidation of the water produces two electrons, and that the formation of NADPH from NADP requires two electrons. These reactions occur at different locations within the chloroplasts and in the process of transferring electrons from the water oxidation site to the NADP reduction site, adenosine diphosphate (ADP) is converted to adenosine triphosphate (ATP see Section 15-5F for discussion of the importance of such phosphorylations). Thus electron transport between the two photoprocesses is coupled to phosphorylation. This process is called photophosphorylation (Figure 20-7). 

In the presence of excess phosphohexose isomerase and glucose-6-phos-phate dehydrogenase the rate of reduction of TPN is proportional to the rate of cleavage of fructose diphosphate. For cases when small, quantities of fructose diphosphate must be used, a second spectrophoto-metric assay, in which fructose diphosphate is regenerated, has been proposed 20). Fructose 6-phosphate is phosphorylated with ATP and phosphofructokinase, and the adenosine diphosphate (ADP) produced is measured with phosphoenolpyruvate and lactic dehydrogenase ... 

Those who are familiar with, or have read the section on DNP are aware of the term "oxidative phosphorylation". This is a process by which cells/mitochondria convert ADP (Adenosine Diphosphate) into ATP (Adenosine Triphosphate). Basically this means adding another phosphate molecule to ADP so that it can be converted back into the body s energy /ATP. But the term keeps kids flunking biology anyway. DNP makes cells waste calories and burn fat by "uncoupling" the oxidative phosphorylation process and making it less efficient, even when at rest. 

The only remaining question is how proton induces the endergonic reaction and, first of all, ADP (adenosine diphosphate) and ATP phosphorylation processes. The following circumstance is of great importance formation of a sufficient amount (generation) of H+ results... 

Figure 8-3. The components of oxidative phosphorylation located in the inner membrane of the mitochondria. ADP, adenosine diphosphate ATP, adenosine triphosphate NADH, nicotinamide adenine dinucleotide.

ATP is produced from ADP (adenosine diphosphate) by coupling the release of electrons to the reaction of organic phosphates and ADP producing ATP. ATP has two modes of production substrate-level phosphorylation and oxidative phosphorylation. In the former, the electrons released by the energy source are absorbed by an intermediate product within the system. The electron absorption is accompanied by an energy release and ATP is formed. The electron-transport system is simple. 

A second phosphorylation reaction follows the isomerization step. Fructose 6-phosphate is phosphorylated by ATP to fructose 1,6-bisphosphate (F-1,6-BP). The prefix bis- in bisphosphate means that two separate monophosphate groups are present, whereas the prefix di- in diphosphate (as in adenosine diphosphate) means that two phosphate groups are present and are connected by an anhydride bond. 

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. 

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