Adenosine 5 -phosphate formation from

Adenosine 3 -phosphate, formation from nonenzymatic hydrolysis of cAMP, 23... 

The reaction probably proceeds through the formation of an imino analogue of mixed anhydrides by nucleophilic displacement of cyanide during the phosphate activation. Cyanogen bromide was found to be more effective than DISN in this transformation. Since higher yields were obtained in the preparation of the cyclic phosphate from 3 -adenosinc phosphate than from 2/-adenosine phosphate, the authors suggested the formation of an activated... 

Pyrolysis of nucleic acids compared to ion fragments formation from adenosine-5 -phosphate and 2-deoxyadenosine-5 -phosphate. 

The three tissue enzymes known to participate in formation of the phosphate esters are (1) thiaminokinase (a pyro-phosphokinase), which catalyzes formation of TPP and adenosine monophosphate (AMP) from thiamine and adenosine triphosphate (ATP) (2) TPP-ATP phosphoryl-transferase (cytosoHc 5"-adenylic kinase)which forms the triphosphate and adenosine diphosphate from TPP and ATP and (3) thiamine triphosphatase, which hydrolyzes TPP to the monophosphate. Although thiaminokinase is widespread, the phosphoryl transferase and membrane-associated triphosphatase are mainly in nervous tissue. 

Nucleoside Pyrophosphates. - The synthesis of 8-aryl-3-P-o-ribofuranosylimiazo[2,l-i]purine 5 -phosphates (122) from AMP or ATP has been described. To access these fluorescent nucleotide derivatives, a combination of Kornblum oxidation reaction and imidazole formation was employed. For this conversion, the appropriate adenosine phosphate, present in its free acid form, was treated with p-nitro-acetophenone in DMSO in the presence of DBU. Treatment of a 5-(chloroethyl)-4-(triazole-l-yl)pyrimidine-nucleoside with benzylhydrazine offered the 6,6-bicyclic pyrimido-pyradazin-7-one, the precursor to (123). This triphosphate was used as a substrate for DNA polymerases. ... 

Brossard, D. The influence of kinetin on formation and ploidy levels of buds arising from N. tabacum pith tissue grown in vitw, Z. Pflanzenphysiol. 78 (1976) 323-333. Brown, D.C.W. and T.A. Thorpe Adenosine phosphate and nicotinamide adenine dinucleotide pool sizes during shoot initiation in tobacco callus Plant Physiol. 65 (1980) 587-590. 

Fig. 31.41 The sulfoconjugation reaction example of 4-nitrophenol as acceptor substrate. Step 1, PAPS formation from adenosine 5 -phosphosulfate (APS) step 2, sulfate conjugation with the subsequent release of 3 -phosphoadenosine 5 -phosphate (PAP) step 3, possible hydrolysis of the sulfoconjugate by arylsulfatases.

After that, aspartic acid transfers another amino moiety, leading to the formation of adenosine-5 -phosphate. Guanosine-5 -phosphate results from addition of water, oxidation and amination, this time by glutamine. 

In the first reaction, a phosphate group from ATP (adenosin triphosphate) is transferred to the substrate with the formation of ADP. 

We may suppose that the photosynthetic organisms learned to recombine products of the photochemical oxidation-reduction reaction in a useful way. The energy released by this recombination was used to bring about the formation of the biological acid anhydrides, such as adenosine triphosphate (ATP) from inorganic phosphate, and organic phosphates such as adenosine diphosphate (ADP). 

Scheme 11.2. The phosphorylation of the carboxylate group of 3-phosphoglycerate to produce a mixed carboxylate-phosphate anhydride, 1,3-bisphosphoglycerate. The phosphoglycerate kinase-catalyzed (EC 2.7.2.3) formation of the anhydride involves the removal of a phosphate group from adenosine triphosphate (ATP), yielding adenosine diphosphate (ADP) and the bisphosphoglycerate. The stereochemistry of the attack at phosphorus is backside to the leaving group.

Scheme 12.97. Formation of adenosine phosphate from inosine. EC numbers and some graphic materials provided in this scheme have been taken from appropriate links in a URL starting with http //www.chem.qmul.ac.uk/iubmb/enzyme/.

A reaction similar in type to that described above has been demonstrated in liver extracts by Wajzer and Baron for inosine-3 -phosphate synthesis from hypoxanthine and ribose-3-phosphate. The formation of the mononucleotide, adenylic acid, by the phosphorylation of adenosine by adenosinetriphosphate has also been described. The significance and integration of these different reactions remains a major problem for future effort. 

The kinase reaction is reversible and the disappearance of aspartyl phosphate in the presence of adenosine diphosphate (ADP) is associated with the stoichiometric formation of ATP. On the assumption that the appearance of ADP and the disappearance of ATP and aspartate are equivalent to aspartyl phosphate formation, the equilibrium constant of the reaction was calculated from the experimental data to be 3.5 X 10 at pH 8.0 and a temperature of 15°. It is to be noted that the /3-aspartokinase reaction is quite analogous to that involving ATP and 3-phosphoglyceric acid. 

The evidence supporting this concept is derived from experiments on yeast extracts and pigeon liver preparations but further joint studies by Lipmann and Lynen make the formation of phosphoryl-ated or pyrophosphorylated coenzyme A improbable and suggest the formation of enzyme-bound adenosine phosphate and coenzyme A. In the presence of purified yeast enzymes isotopic pyrophosphate was found to exchange the isotope with ATP in the absence of coenzyme A. This excludes the latter as an obligatory participant. Isotopic acetate also exchanged readily with acetyl coenzyme A in the presence of this yeast enzyme. The following scheme of 3 reactions fits the facts ... 

Several investigators had observed the formation of hexose phosphates during nucleoside and pentose metabolism by cell extracts. It was considered until recently that these hexose phosphates arose from a reversal of the Embden-Meyerhof scheme operative on triose phosphate derived from pentose. It has now been found by Dische that more hexose may be generated from adenosine in hemolysates than would be expected from the proportion of 3-carbon fragments in the pentose molecule, i.e., 0.75 mole hexose per mole pentose instead of a maximal 0.6. Furthermore, much of the carbon of the pentose was in hexose monophosphate produced under conditions in which hexose-6-phosphate and hexose-1,6-diphosphate were not interconvertible. 

The structure and formation of ATP. (A) The chemical structure of adenosine triphosphate (ATP). "C" indicates carbon, "N" nitrogen, "O" oxygen, "H" hydrogen and "P" phosphorus. Note the negative charges on the phosphate groups (PO3 ). (B) ATP can be formed from adenosine diphosphate (ADP). 

A similar reaction mechanism was proposed by Chin et al. [32] for the hydrolysis of the biological phosphate monoester adenosine monophosphate (AMP) by the complex [(trpn) Co (OH2)]2+ [trpn = tris(ami-nopropyl)amine]. Rapid cleavage is observed only in the presence of 2 equiv metal complex. It is evident from 31P NMR spectra that on coordination of 1 equiv (trpn)Co to AMP a stable four-membered chelate complex 4 is formed. The second (trpn)Co molecule may bind to another oxygen atom of the substrate (formation of 5) and provide a Co-OH nucleophile which replaces the alkoxy group. The half-life of AMP in 5 is about 1 h at pD 5 and 25 °C. 

Mansour, T. E., Sutherland, E. W., Rail, T. W., and Bueding, E. (1960) The effect of serotonin (5-hydroxytryptamine) on the formation of adenosine 3, 5 -phosphate by tissue particles from the liver fluke, Fasciola hepatica. J. Biol. Chem., 235 466-470. 

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