67030-27-7Relevant articles and documents
Photolabile 1-(2-Nitrophenyl)ethyl Phosphate Esters of Adenine Nucleotide Analogues. Synthesis and Mechanism of Photolysis
Walker, Jeffery W.,Reid, Gordon P.,McCray, James A.,Trentham, David R.
, p. 7170 - 7177 (2007/10/02)
A general method is described for preparing photolabile 1-(2-nitrophenyl)ethyl esters of phosphate and thiophosphate compounds.The method is based on selective alkylation of weakly ionizing phosphate groups by a new alkylating agent, 1-(2-nitrophenyl)diazoethane.ATP and the widely used structural analogues of ATP, 5'-adenylyl imidodiphosphate (ATP(β,γNH)) and adenosine 5'-(3-thiophsophate) (ATP(γS)), were alkylated on the terminal (γ) phosphate group.ATP(γS) was alkylated on oxygen or on sulfur in approximately equal amounts.Photolysis of P3-1-(2-nitrophenyl)ethyladenosine 5'-triphosphate, commonly called "caged ATP", was analyzed spectroscopically at pH values close to neutral in aqueous solvents by use of laser pulse photolysis.The kinetics of formation of the three products, ATP, 2-nitrosoacetophenone, and H+, were each monitored, as well as the kinetics of formation and decay of an intermediate presumed to be an aci-nitro compound (apparent ε406nm = 9.1 x 103 M-1 cm-1).For caged ATP in the presence of 3 mM MgCl2, and aci-nitro intermediate and H+ formed first at > 105 s-1 followed by the decay of the intermediate at 86 s-1 at pH 7.1, 21 deg C, and ionic strength 0.18 M.ATP, monitored by a biochemical assay, and 2-nitrosoacetophenone, monitored by a characteristic absorption band at 740 nm, were formed simultaneously with the decay of the intermediate under all conditions tested.The rate of decay of the aci-nitro intermediate was therefore used as a measure of the rate of release of the nucleotide analogues from their photolabile precursors.At pH 7.1, 0.18 M ionic strength, and 21 deg C the rate constants ranged from 35 to 250 s-1 and displayed a similar dependence on pH as caged ATP.The steady-state quantum yields of the 1-(2-nitrophenyl)ethyl phosphate esters were in the range 0.49 - 0.63.The deleterious effect of 2-nitrosoacetophenone on biological materials can be avoided by having thiols present.The reaction kinetics of dithiothreitol and 2-nitrosoacetophenone was described by a two-step process, the first step having a rate constant of 3.5 x 103 M-1 s-1 and the second 45 s-1 at pH 7.0, 21 deg C, and ionic strength 0.18 M.
Rapid photolytic release of adenosine 5'-triphosphate from a protected analogue: Utilization by the Na:K pump of human red blood cell ghosts
Kaplan,Forbush III,Hoffman
, p. 1929 - 1935,1930, 1932 (2007/10/05)
2-Nitrobenzyl phosphate and 1-(2-nitro)phenylethyl phosphate have been synthesized and demonstrated to be suitable as photolabile sources of inorganic phosphate. The same protecting groups were attached to the terminal phosphate of adenosine 5'-triphosphate. These 'caged ATP' compounds released adenosine 5'-triphosphate on illumination at 340 nm in aqueous solution and P3-1-(2-nitro)phenylethyl-ATP gave about a 70% yield in under 30 s. The unphotolyzed caged ATP was neither a substrate nor inhibitor of purified renal Na,K-ATPase (EC 3.6.1.3). Following photolysis in the presence of the enzyme, the liberated ATP was hydrolyzed but at an inhibited rate. The photo-dependent inhibition could be eliminated by prior addition of glutathione or bisulfite to the irradiated solution. Caged ATP was incorporated into resealed human erythrocyte ghosts prepared from red blood cells depleted of internal energy stores. While the Na:K pump was unable to use incorporated caged ATP as a substrate, the ATP liberated by photolysis activated the pump as evidenced by measurements of K-dependent, ouabain-sensitive Na efflux. Thus the caged ATP can be used as a stable source of ATP unmetabolizable by intracellular ATPases until the ATP is released following photolytic irradiation.
