The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD spectra five cation–cytosine exhibit both similar distinctive spectral features over the range ~1000–1900 cm-1. Li+(cytosine), Na+(cytosine), K+(cytosine) relatively simple but changes in shape shifts positions several bands that correlate with size cation. Rb+(cytosine)...

Rearranged: The attachment of gas-phase divalent metal ions that bind as strongly Mg2+ and transition-metal to the dipeptide PhePhe results in displacement amide proton by newly characterized iminol tautomerization rearrangment. More weakly coordinating known charge-solvation mode. Infrared multiple-photon dissociation spectroscopy using free-electron laser clearly shows tautomeric transition. Detailed facts importance specialist readers are published "Supporting Information". Such documents...

Vibrational ion spectroscopy techniques coupled with mass spectrometry are applied to standard metabolites as a proof-of-principle demonstration for the structural identification of unknown metabolites. The traditional room temperature infrared multiple photon dissociation (IRMPD) technique is shown differentiate chemical moieties in isobaric and isomeric variants. These results compared spectra cryogenically cooled analyte ions, showing enhanced spectral resolution, thus also improved...

The detailed chemical information contained in the vibrational spectrum of a cryogenically cooled analyte ion would, principle, make infrared (IR) spectroscopy gold standard technique for molecular identification mass spectrometry. Despite this immense potential, there are considerable challenges both instrumentation and methodology to overcome before is analytically useful. Here, we discuss promise IR small molecule analysis context metabolite identification. Experimental strategies address...

Carbohydrates and their derivatives play important roles in biological systems, but isomeric heterogeneity also presents a considerable challenge for analytical techniques. Here, stepwise approach using infrared multiple-photon dissociation (IRMPD) via tunable CO2 laser (9.2–10.7 μm) was employed to characterize variants of glucose-based trisaccharides. After the deprotonated trisaccharides were trapped fragmented disaccharide C2 fragments Fourier transform ion cyclotron resonance (FTICR)...

Tandem-ion mobility spectrometry/mass spectrometry methods have recently gained traction for the structural characterization of proteins and protein complexes. However, ion activation techniques currently coupled with tandem-ion are limited in their ability to characterize structures complexes.Here, we describe coupling separation capabilities tandem-trapped (tTIMS/MS) dissociation ultraviolet photodissociation (UVPD) structure analysis.We establish feasibility dissociating intact by UV...

Three lithiated N-acetyl-D-hexosamine (HexNAc) isomers, N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-galactosamine (GalNAc), and N-acetyl-D-mannosamine (ManNAc) are investigated as model monosaccharide derivatives by gas-phase infrared multiple-photon dissociation (IRMPD) spectroscopy. The hydrogen stretching region, which is attributed to OH NH modes, reveals some distinguishing spectral features of the lithium-adducted complexes that useful in terms differentiating these isomers. In order...

It has been suggested that small losses from reduced peptide molecular species in electron capture dissociation (ECD) could indicate the presence of certain amino acids [H.J. Cooper, R.R. Hudgins, K. Håkansson and A.G. Marshall, J. Am Soc. Mass Spectrom 13, 241 (2002)], similarly to immonium ions high-energy collision-activated dissociation. The diagnostic value ECD (M•–X) region (1 Da ≤ X 130 Da) was tested on several synthetic peptides. insufficiency existing knowledge for making correct...

We report infrared multiple photon dissociation (IRMPD) spectra for a series of crown-adducted, protonated amino acids, generated by electrospray ionization. The tight chelation 18-crown-6 on the NH(3)(+) moiety results in considerable red shift stretch modes, notably antisymmetric stretch. This is rationalized distortion normal mode potential energy surface, as verified quantum chemical calculations. On other hand, local oscillator such carboxylic acid OH stretch, indole NH and phenol...

The post-translational modifications sulfation and phosphorylation pose special challenges to mass spectral analysis due their isobaric nature lability in the gas phase, as both types of peptides dissociate through similar channels upon collisional activation. Here, we present resonant infrared photodissociation based on diagnostic sulfate phosphate OH stretches, a means differentiate sulfated from phosphorylated within framework spectrometry platform. approach is demonstrated for number...

Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy density functional theory (DFT) computations. The in the 1500-1800 cm(-1) region is found to be conformationally informative; particular, frequency C═O stretching mode terminal carboxyl group diagnostic for hydrogen bonding hydroxyl. alkaline earth (Ca(2+) Ba(2+)) enforce a highly structured chelation...

We present an infrared laser-based mass spectrometric strategy to differentiate peptides that are phosphorylated (i.e., containing pS, pT, or pY) from those nonphosphorylated S, T, Y), and have none of these moieties neither pY nor Y). This is demonstrated for a series tripeptides two larger octapeptides, showing the diagnostic phosphate OH stretch (indicative can be distinguished alcohol In addition, multiple photon dissociation (IRMPD) spectra peptide analytes recorded simultaneously in...

Spectral fingerprints: Collision-induced dissociation (CID) of protonated peptides in the gas phase results linear fragment ions with a five-membered oxazolone ring on their C-terminal side. Infrared spectroscopy confirms that smaller fragments adopt structures. Conversely, mid-sized and larger an isomerization to "head-to-tail" macrocycles is observed (see picture). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not...

We demonstrate operation of the first cryogenic 2D linear ion trap (LIT) with mass‐selective capabilities. This presents a number advantages for infrared “action” spectroscopy studies, particularly those employing “tagging/messenger” approach. The high trapping efficiencies, capacities, and low detection limits make LITs highly suitable choice low‐concentration analytes from scarce biological samples. In our trap, ions can be cooled down to temperatures achieve higher‐resolution spectra,...

Very highly charged proteins, so-called "supercharged" ions, can lose (excess) protons to background gases like N2 . It is remarkable that such extremely acidic species be generated in electrospray ionization, the presence of not just but also much higher-basicity solvents. What mechanism(s) explain high charging, and what ultimate limit?