Adenosine phosphates metal complexes

Adenosine-5 -monophosphate lanthanide complexes NMR, 3,1104 Adenosine phosphates metal complexes, 2, 977 6, 445 Adenosine 5 -triphosphate... 

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. 

Table 11 Log Formation Constants of Some 1 1 Divalent Metal Complexes of Adenosine Phosphates ...

Toropov, A.A. and Toropova, A.P. (2001c) QSPR modeling of stability of complexes of adenosine phosphate derivatives with metals absent from the complexes of the teaching access. Russ. J. Coord. Chem., 27, 574-578. 

Thioanalogues of adenosine phosphates have been studied by n.m.r. and the chemical shifts were compared to those of the oxygenated compounds. The effects of changing pH and the concentration of added Mg + led to the conclusion that chemical shift data cannot yield unequivocal information concerning the absolute structure of the metal complexes of nucleosides but can be used to monitor changes in chelation, for example, in binding to enzymes. ... 

Toropov et al.76-79 developed QSPR models for the complexes of nine alkaline-earth and transition metals with some amino acids, phosphate derivatives of adenosine, and heterocyclic compounds based on topological indices. Although the numbers of examples in the datasets were big enough, 11076 and 150,79 they involved only a few different ligands (17 and 25 molecules, respectively). The validation calculations were performed on the test sets containing the same ligands as in the training sets, which could explain the well observed performance of the predictions.7679... 

Another dinuclear Zn complex with A(,A/ ,A(, N -tetrakis[(2-pyridyl) methyl]-2-hydroxy-l,3-diaminopropane was shown to be able to achieve phosphodiester cleavage of diribonucleotide ApA at 50°C and neutral pH 355) (16, Fig. 17). The hydrol5dic cleavage of ApA was significantly accelerated by the cooperation of two metals in the binu-clear complex because the mononuclear complex was inactive in comparable experimental conditions. The pseudo-first-order rate constant is 1.9 X 10 sec (half-life 10 hr) (ApA, 100 /aM ZnCL, 5 mM ligand, 2.5 mM). Deprotonation of 2 -OH by a metal hydroxo would be involved in the mechanism of reaction because the products of cleavage were adenosine, adenosine 2 - or 3 -phosphate, and 2, 3 -cAMP. 

Hydrogen peroxide produced by reduction of is relatively innocuous and has limited reactivity in the absence of metals. However, in the presence of Fe +, H O produces the very reactive hydroxyl radical (HO ) by the so-called Fenton reaction (see Chapter 13). Iron compounds complexed with phosphate esters (adenosine di- and triphosphate, ADP and ATP) can decompose H O to form free radicals. The presence of the ADP-Fe complex in plant and animal foods may trigger the reduction of H O to form the very reactive and potentially damaging hydroxyl radicals (3). 

The 3, 5 -cyclic monophosphate of adenosine (cAMP) (2.148) is an important secondary messenger for intercellular communication in biochemistry. When the cell is stimulated by the first messenger, compound 2.148 is formed from adenosine triphosphate (ATP) (Scheme 2.25). This reaction is catalysed by an adenosine cyclase enzyme. The cAMP then goes on to activate other intracellular enzymes, so producing a cell response. The response is terminated by the hydrolysis of cAMP by phosphodiesterase (a phosphate-ester-hydrolysis enzyme). The action of adenylate cyclase has been mimicked successfully with a p-cyclodextrin complex of Pr(iii) and other lanthanide(iii) metals, under physiological conditions. The... 

---