Phosphate cleavage

Pj release occurs at a relatively apparent slow rate (kobs = 0.005 s" ), so that the transient intermediate F-ADP-Pj in which P is non-covalently bound, has a life time of 2-3 minutes (Carlier and Pantaloni, 1986 Carlier, 1987). While the y-phosphate cleavage step is irreversible as assessed by 0 exchange studies (Carlier et al., 1987), the release of Pi is reversible. Binding of H2PO4 (Kp 10 M) causes the stabilization of actin filaments and the rate of filament growth varies linearly with the concentration of actin monomer in the presence of Pi (Carlier and Pantaloni, 1988). Therefore, Pi release appears as the elementary step responsible for the destabilization of actin-actin interactions in the filament. 

Phosphotransferases with a phosphate cleavage is sequence-specific... 

Samuni A, Neta P (1973) Flydroxyl radical reaction with phosphate esters and the mechanism of phosphate cleavage. J Phys Chem 77 2425-2429... 

Salomon J, Elad D (1973) Photochemical reactions of nucleic acid constituents. Peroxide-initiated reactions of purines with alcohols. J Org Chem 38 3420-3421 Salomon J, Elad D (1974) Ultraviolet and y-ray-induced reactions of nucleic acid constituents. Reactions of purines with amines. Photochem Photobiol 19 21-27 Samuni A, Neta P (1973) Hydroxyl radical reaction with phosphate esters and the mechanism of phosphate cleavage. J Phys Chem 77 2425-2429... 

Zheng Y, Cloutier P, Hunting DJ, Sanche L, Wagner JR (2005). Chemical basis of DNA sugar-phosphate cleavage by low-energy electrons. J Am Chem Soc 127 16592-16598. 

Thiosugars can be rapidly synthesized when sulfur-substituted aldehydes are condensed with DHAP under the influence of FDP aldolase.42 The synthesis of these heterocycles is completed by phosphate cleavage, acetylation and reduction of the resultant ketone (Scheme 5.20). Cyclitols, another interesting class of biologically active compounds, have been prepared through the reaction of phosphonate- and nitro-substituted aldehydes with DHAP under the influence of FDP aldolase (Scheme 5.21) 43,436... 

High levels of ADP formed in the myofibrils during contraction favor the reverse reaction namely, resynthesis of ATP - at the expense of creatine phosphate cleavage to creatine. This example shows that one must consider not only the standard free energy change but also the actual concentrations of all reactants and products when predicting the direction of a reaction in vivo. 

S5Hiergistic effects between two different metals could also promote the phosphate cleavage (349-351). All these data suggested that it was possible to prepare and to use dinuclear complexes to promote the hydrolysis of phosphodiester linkages (308, 352-355). 

Fig. 19. Neomycin binding to the hammerhead ribozyme. Protonated amino groups of neomycin (in blue) are shown as red spheres and are compared with the positions of ions (white spheres). The phosphate cleavage site is depicted in yellow. Reprinted with permission, Copyright 1998 Elsevier.

Fig. 24.29 (a) Chemical structure of l,3-guanidinocalix[4]arene 77. (b) Bifunctional general acid-base catalysis of monoprotonated guanidinocalix[4]arene in the transesterification of HPNP. (c) Diribonucleotide phosphate cleavage [91, 92]... 

This concept was now transferred very successfully to diribonucleotide phosphate cleavage by Salvio et al. Rate accelerations approach 100,000-fold with the most favorable substrate catalyst combinations 1,2-diguanidiniocalixarene and CpA as well as GPU [92]. 

Bald, I., Dabkowska, I., 8c Illenberger, E. (2008). Probing biomolecules by laser-induced acoustic desorption Electrons at near zero electron volts trigger sugar-phosphate cleavage. Angewandte Chemie International Edition, 47, 8518. 

For preparative purposes, titanium metal can be used in place of sodium or lithium in liquid ammonia for both the vinyl phosphate and aryl phosphate" cleavages. The titanium metal is generated in situ from TiCla by reduction with potassium metal in tetrahydrofuran. 

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