Stabilization of Excess Charge in Isolated Adenosine 5‘-Triphosphate and Adenosine 5‘-Diphosphate Multiply and Singly Charged Anions

Abstract

Multiply charged anions (MCAs) represent highly energetic species in the gas phase but can be stabilized through formation of molecular clusters with solvent molecules or counterions. We explore the intramolecular stabilization of excess negative charge in gas-phase MCAs by probing the intrinsic stability of the [adenosine 5'-triphosphate-2H](2-) ([ATP-2H](2-)), [adenosine 5'-diphosphate-2H](2-) ([ADP-2H](2-)), and H(3)P(3)O(10)(2-) dianions and their protonated monoanionic analogues. The relative activation barriers for decay of the dianions via electron detachment or ionic fragmentation are investigated using resonance excitation of ions isolated within a quadrupole trap. All of the dianions decayed via ionic fragmentation demonstrating that the repulsive Coulomb barriers (RCB) for ionic fragmentation lie below the RCBs for electron detachment. Both the electrospray ionization mass spectra (ESI-MS) and total fragmentation energies for [ATP-2H](2-), [ADP-2H](2-), and H(3)P(3)O(10)(2-) indicate that the multiply charged H(3)P(3)O(10)(2-) phosphate moiety is stabilized by the presence of the adenosine group and the stability of the dianions increases in the order H(3)P(3)O(10)(2-) < [ADP-2H](2-) < [ATP-2H](2-). Fully optimized, B3LYP/6-31+G* minimum energy structures illustrate that the excess charges in all of the phosphate anions are stabilized by intramolecular hydrogen bonding either within the phosphate chain or between the phosphate and the adenosine. We develop a model to illustrate that the relative magnitudes of the RCBs and hence the stability of these ions is dominated by the extent of intramolecular hydrogen bonding.

Tandem mass spectrometry for the analysis of self‐sorted pseudorotaxanes: the effects of Coulomb interactions

“…[25] Quite a number of multiply charged supramolecules have been studied in the gas phase [26 -31] -however with little attention to the effects of different charge states on the stability and fragmentation patterns. [27,32] The effects of charge repulsion can differ depending on where the charge is located in a non-covalent complex. Figure 1 shows three typical situations for a ditopic guest and its complex.…”

Analysis of endogenous ATP analogs and mevalonate pathway metabolites in cancer cell cultures using liquid chromatography–electrospray ionization mass spectrometry

“…The collision energies yielding highest signal intensities for each compound were 15 V, 27 V and 30 V, respectively. Typically fragmentation occurred at the site of the phosphate ester bonds and fragments such as a phosphate group [44] were cleaved. Other fragment ions were also observed when lower collision energies were applied.…”

Gas phase conversion of triphosphate to trimetaphosphate

“…[5] The loss of H 2 O molecule has been detected also for anion H 4 P 3 O 10 À (tetrahydrogen triphosphate anion); however, the signal had minor abundance. [6] Taking into accounts the importance of phosphate anions (present in biological systems), it is interesting to study phosphate anions in the gas phase. Gas phase properties reveal the intrinsic properties of studied ions, in the absence of solvent.…”

“…In these conditions, only singly charged ions Na n H m P 3 O 10 À (n+m=4) were generated (it is worth adding that under different conditions generation of doubly charged ions H 3 P 3 O 10 À2 is possible [13] ). ) has been added to the ATP solution (although sometimes sodium containing ions of ATP can be generated without addition of sodium cations [6] ). Addition of NaCl did not allow generation of abundant ions of interest.…”