Absolute Thermodynamic Measurements of Alkali Metal Cation Interactions with a Simple Dipeptide and Tripeptide

Abstract

Absolute bond dissociation energies (BDEs) of glycylglycine (GG) and glycylglycylglycine (GGG) to sodium and potassium cations and sequential bond energies of glycine (G) in Na+G2 were determined experimentally by threshold collision-induced dissociation (TCID) in a guided ion beam tandem mass spectrometer. Experimental results showed that the binding energies follow the order of Na+ > K+ and M+GGG > M+GG > M+G. Theoretical calculations at the B3LYP/6-311+G(d) level show that all complexes had charge-solvated structures (nonzwitterionic) with either [CO,CO] bidentate or [N,CO,CO] tridentate coordination for M+GG complexes, [CO,CO,CO] tridentate or [N,CO,CO,CO] tetradentate coordination for M+GGG complexes, and [N,CO,N,CO] tetradentate coordination for Na+G2. Ab initio calculations at three different levels of theory (B3LYP, B3P86, and MP2(full) using the 6-311+G(2d,2p) basis set with geometries and zero-point energies calculated at the B3LYP/6-311+G(d) level) show good agreement with the experimental bond energies. This study demonstrates for the first time that TCID measurements of absolute BDEs can be successfully extended to biological molecules as complex as a tripeptide.

Experimental and Theoretical Studies of Sodium Cation Interactions with the Acidic Amino Acids and Their Amide Derivatives

“…20,22 Metal-ligand complexes are then extracted from the source and mass selected using a magnetic momentum analyzer. The mass-selected ions are decelerated to a well-defined kinetic energy and are focused into a rf octopole ion guide that traps the ions radially.…”

Hydration–dehydration interactions between glycine and anhydrous salts: Implications for a chemical evolution of life

“…SaltÁGlyGly + Gly) < 0). In that case, the complexations decrease the D r G 0 of Gly polymerization further in addition to the salt hydrations as: As for complexation with isolated cations in the gas phases, Gly polymers are known to form more stable complexes than Gly due to strong binding energies with the cations (Ye and Armentrout, 2008;Constantino et al, 2009). The difference in stability can decrease the D r G 0 of Gly polymerization.…”

“…The linear relationship indicates that as cation-H 2 O complex becomes thermodynamically more stable, the corresponding cation-Gly complex also becomes more stable. Additionally, the increase in stability of cation-Gly complexes tends to increase the stability of corresponding cationGly polymer complexes more strongly, and consequently the difference between the stability of cation-Gly complex and that of corresponding cation-Gly polymer complex also increases Rode, 2001, 2004;Ye and Armentrout, 2008;Constantino et al, 2009). Thus, as the salt hydration decreases the D r G 0 of Gly polymerization, the complexation of Gly (and Gly polymers) with the corresponding salt is expected to also decrease the D r G 0 more largely.…”

Structure of sodiated octa-glycine: IRMPD spectroscopy and molecular modeling

“…In this context, sodiated oligoglycines have been used in the last decade as a valuable testing ground for new experimental developments designed to obtain refined energetic and/or structural data. These include ion mobility measurements for global shape information [9,10], H/D exchange extent and kinetics for isomeric/ conformational content [11], the kinetic [12,13] and the threshold collision induced decomposition [14] methods for thermochemical measurements, as well as infrared multiple photon dissociation (IRMPD) spectroscopy [15] for identification of functional groups and their interactions. All these studies have been complemented by extensive molecular modeling as required for translating experimental data into properties of specific molecular structures.…”