The Interaction of the Dipeptide Carnosine With Alkali Metal Ions Studied by Ion Trap Mass Spectrometry

Abstract

The complexation of alkali metal ions and the proton X + (X = H, Li, Na, K, Rb, Cs) by β-alanyl-L-histidine (carnosine, Car) was investigated by electrospray ionization mass spectrometry (ESI-MS) and MS/MS fragmentation studies. Collision-induced dissociation (CID) breakdown curves were recorded and the resulting apparent activation energies were compared to DFT calculations of binding energies at the B3LYP/cc-pVDZ level of theory. Additionally, the influence of metal complexation on hydrogen/deuterium exchange of CarX + with D 2 O was tested. Our investigations characterize the structures of Car-alkali complexes and elucidate the interaction with the differently sized solvated metal cations.

Investigation of protonated and sodiated leucine-enkephalin by hydrogen–deuterium exchange and theoretical calculations

“…There are a few studies on HDX between sodiated peptides and D 2 O, 9,16,30,[40][41][42] however, to the best of our knowledge, the HDX mechanism of these reactions is still unclear.…”

“…The HDX performance of LE is similar to that of polyamine 13 and peptides of gramicidin S 38 and Arg-Gly-Asp, 39 but contrary to other peptides, 10,40,41 such as bradykinin, for which the single metal ion adduction can signicantly increase the HDX reactivity. There are a few studies on HDX between sodiated peptides and D 2 O, 9,16,30,[40][41][42] however, to the best of our knowledge, the HDX mechanism of these reactions is still unclear.…”

Oxaliplatin complexes with carnosine and its derivatives: in vitro cytotoxicity, mass spectrometric and computational studies with a focus on complex fragmentation

“…21 Several explanations were given for these observations including the difference in proton affinities of OxPt and M. 21 The proton affinity of OxPt at 298 K was previously reported to be 233.5 kcal mol À1 , 21 whereas the proton affinities of carnosine, anserine and N-acetyl-carnosine are calculated here to be 254.4, 255.9 and 250.2 kcal mol À1 respectively. To the best of our knowledge the proton affinities of anserine and N-acetyl-carnosine are the first reported values in the literature while three previously calculated values for the proton affinities of carnosine were given at 256.5 (at 0 K), 57 245.4, 58 and 232.98, 59 kcal mol À1 . The latter of these values most likely needs to be revisited as it is significantly lower than all other calculated values and the only available experimental value for the proton affinity of carnosine of 244.59 kcal mol À1 obtained by the Graham Cooks method.…”

Intermetallic Competition in the Fragmentation of Trimetallic Au–Zn–Alkali Complexes

“…The fit parameter is the amplitude at which the sigmoid function is at half the maximum value, whereas B describes the rise of the sigmoid curve. Owing to the correlation of the fragmentation amplitude and appearance energy, it is feasible to assume that the appearance curves can be associated with the relative stability of the cationized alkali adducts . The according plots are available in the Supporting Information.…”