Rearrangement of Proline Complexes with Zn: An Infrared Multiple Photon Dissociation and Theoretical Investigation.

Complexes of proline (Pro) cationized with Zn and Cd were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free electron laser. Complexes of intact Pro with CdCl, CdCl(Pro), a complex of (Zn+Pro-H) where a proton has been lost, as well as Zn(Pro-H)(Pro) were formed by electrospray ionization. In order to identify the structures formed experimentally, the IRMPD spectra were compared to those calculated from optimized structures at the B3LYP/6-311+G(d,p) level for zinc complexes and B3LYP/def2-TZVP level with an effective core potential on cadmium for the CdCl(Pro) system.

Infrared Spectroscopic Characterization of Early 4d Transition Metal Carbene Cations, ZrCH and NbCH.

IR multiple-photon dissociation (IRMPD) action spectroscopy is combined with quantum chemical calculations to examine the [M,C,2H] species for the early 4d metals, M = Zr and Nb. These ions were formed by reacting laser ablated M ions with cyclopropane (-CH) in a molecular beam apparatus. Both IRMPD spectra exhibit one major band near 700 cm and a second weaker band at about twice that wavenumber, more evident when irradiated in focus.

Infrared multiple-photon dissociation spectroscopy of cationized glycine: effects of alkali metal cation size on gas-phase conformation.

The gas-phase structures of cationized glycine (Gly), including complexes with Li, Na, K, Rb, and Cs, are examined using infrared multiple-photon dissociation (IRMPD) spectroscopy utilizing light generated by a free electron laser, in conjunction with calculations. To identify the structures present in the experimental studies, measured IRMPD spectra are compared to spectra calculated at B3LYP/6-311+G(d,p) for the Li, Na, and K complexes and at B3LYP/def2TZVP for the Rb and Cs complexes. Single-point energy calculations were carried out at the B3LYP, B3P86, and MP2(full) levels using the 6-311+G(2d,2p) basis set for Li, Na, K and the def2TZVPP basis set for Rb and Cs.

Sodium Binding Interactions with Aliphatic Amino Acids: A Guided Ion Beam and Computational Study.

Metal binding affinities play a vital role in medicinal, biological, and industrial applications. In particular, metal cation-amino acid (AA) interactions contribute to protein stability such that analyzing analogous prototypical interactions is important. Here, we present a full description of the interactions of sodium cations (Na) and six aliphatic amino acids (AA), where AA = glycine (Gly), alanine (Ala), homoalanine (hAla), valine (Val), leucine (Leu), and isoleucine (Ile).

Infrared Multiple-Photon Dissociation Spectra of Sodiated Complexes of the Aliphatic Amino Acids.

Sodiated complexes of the aliphatic amino acids, Gly, Ala, Val, Leu, and Ile, were examined with infrared multiple-photon dissociation action spectroscopy utilizing light from a free-electron laser. To identify structures, the experimental spectra were compared to linear spectra calculated at the B3LYP/6-311+G(d,p) level of theory. Relative energetics of all complexes were calculated at B3LYP, B3P86, MP2(full), B3LYP-GD3BJ, and M06-2X levels using a 6-311+G(2d,2p) basis set.

Influence of a Hydroxyl Group on the Deamidation and Dehydration Reactions of Protonated Asparagine-Serine Investigated by Combined Spectroscopic, Guided Ion Beam, and Theoretical Approaches.

Deamidation of asparaginyl (Asn) peptides is a spontaneous post-translational modification that plays a significant role in degenerative diseases and other biological processes under physiological conditions. In the gas phase, deamidation of protonated peptides is a major fragmentation channel upon activation by collision-induced dissociation. Here, we present a full description of the deamidation process from protonated asparagine-serine, [AsnSer+H], via infrared (IR) action spectroscopy and threshold collision-induced dissociation (TCID) experiments in combination with theoretical calculations.

Zinc and cadmium complexation of L-methionine: An infrared multiple photon dissociation spectroscopy and theoretical study.

Methionine (Met) cationized with Zn , forming Zn (Met-H) (ACN) where ACN = acetonitrile, Zn (Met-H) , and ZnCl (Met), as well as Cd , forming CdCl (Met), were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from the FELIX free electron laser. A series of low-energy conformers for each complex was found using quantum-chemical calculations in order to identify the structures formed experimentally. For all four complexes, spectral comparison indicated that the main binding motif observed is a charge solvated, tridentate structure where the metal center binds to the backbone amino group nitrogen, backbone carbonyl oxygen (where the carboxylic acid is deprotonated in two of the Zn complexes), and side-chain sulfur.

Zinc and Cadmium Complexation of l-Threonine: An Infrared Multiple Photon Dissociation Spectroscopy and Theoretical Study.

Complexes of threonine (Thr) cationized with Zn and Cd were examined by infrared multiple photon dissociation action spectroscopy using light generated from a free electron laser. Low-energy conformers for Zn(Thr-H)(ACN) (where ACN = acetonitrile), Zn(Gly-H)(ACN) (formed via CO-laser irradiation of intact Zn(Thr-H)(ACN)), and CdCl(Thr) complexes were found using quantum chemical calculations in order to identify the structures formed experimentally. For all species, the predicted ground structures reproduce the experimental spectra well, where tridentate [N, CO, OH] binding motifs were dominantly observed for the intact Zn(Thr-H)(ACN) and CdCl(Thr) complexes.

Experimental and theoretical investigations of infrared multiple photon dissociation spectra of lysine complexes with Zn and Cd.

The gas-phase structures of zinc and cadmium complexes of lysine (Lys) are investigated via a combination of infrared multiple photon dissociation action spectroscopy and ab initio quantum chemical calculations. In order to unambiguously identify the experimentally observed species, [Zn(Lys-H)] and CdCl(Lys), the action spectra were compared to linear absorption spectra calculated at the B3LYP level of theory, using 6-311+G(d,p) and def2-TVZP basis sets for the zinc and cadmium systems, respectively. Single point energies were also calculated at the B3LYP, B3P86, MP2, and B3LYP-GD3BJ (accounting for empirical dispersion) levels of theory using larger basis sets.

Protonated Asparaginyl-Alanine Decomposition: a TCID, SORI-CID, and Computational Analysis.

Deamidation of asparagine residues, one of the fastest known post-translational modifications in proteins, plays a significant role in various biological functions and degenerative, aging diseases. Here, we present a full description of deamidation (as well as other key dissociation processes) from protonated asparaginyl-alanine, H(AsnAla), by studying its kinetic energy-dependent threshold collision-induced dissociation (TCID) with Xe using a guided ion beam tandem mass spectrometer. Relative thresholds compare favorably with those acquired by sustained off-resonance irradiation-CID of H(AsnAla) with Ar in a Fourier transform ion cyclotron resonance mass spectrometer.

Experimental and theoretical investigations of infrared multiple photon dissociation spectra of arginine complexes with Zn and Cd.

Arginine (Arg) complexes with Zn2+ and Cd2+ were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light from a free electron laser. Electrospray ionization generated complexes of deprotonated Arg with Zn2+, [Zn(Arg-H)]+, and Arg with CdCl+, CdCl+(Arg). Possible low-energy conformers of these species were found using quantum chemical calculations, and their calculated IR spectra were compared to experimentally measured IRMPD spectra.

Spectroscopic Identification of the Carbyne Hydride Structure of the Dehydrogenation Product of Methane Activation by Osmium Cations.

The present work explores the structures of species formed by dehydrogenation of methane (CH) and perdeuterated methane (CD) by the 5d transition metal cation osmium (Os). Using infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory (DFT), the structures of the [Os,C,2H] and [Os,C,2D] products are explored. This study complements previous work on the related species formed by dehydrogenation of methane by four other 5d transition metal cations (M = Ta, W, Ir, and Pt).

Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Aspartic Acid Complexes with Zn and Cd.

Complexes of aspartic acid (Asp) cationized with Zn: Zn(Asp-H), Zn(Asp-H)(ACN) where ACN = acetonitrile, and Zn(Asp-H)(Asp); as well as with Cd, CdCl(Asp), were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free electron laser. A series of low-energy conformers for each complex was found using quantum chemical calculations to identify the structures formed experimentally. The main binding motif observed for the heavy-metal complex, CdCl(Asp)[N,CO,CO], is a charge-solvated, tridentate structure, where the metal center binds to the backbone amino group and carbonyl oxygens of the backbone and side-chain carboxylic acids.

Structures of the dehydrogenation products of methane activation by 5d transition metal cations revisited: Deuterium labeling and rotational contours.

A previous infrared multiple photon dissociation (IRMPD) action spectroscopy and density functional theory (DFT) study explored the structures of the [M,C,2H] products formed by dehydrogenation of methane by four, gas-phase 5d transition metal cations (M = Ta, W, Ir, and Pt). Complicating the analysis of these spectra for Ir and Pt was observation of an extra band in both spectra, not readily identified as a fundamental vibration. In an attempt to validate the assignment of these additional peaks, the present work examines the gas phase [M,C,2D] products of the same four metal ions formed by reaction with perdeuterated methane (CD).

Correction: Experimental and theoretical investigations of infrared multiple photon dissociation spectra of glutamic acid complexes with Zn and Cd.

Correction for 'Experimental and theoretical investigations of infrared multiple photon dissociation spectra of glutamic acid complexes with Zn and Cd' by Georgia C. Boles et al., Phys.

Correction: Structural characterization of gas-phase cysteine and cysteine methyl ester complexes with zinc and cadmium dications by infrared multiple photon dissociation spectroscopy.

Correction for 'Structural characterization of gas-phase cysteine and cysteine methyl ester complexes with zinc and cadmium dications by infrared multiple photon dissociation spectroscopy' by Rebecca A. Coates et al., Phys.

Correction: Zn and Cd cationized serine complexes: infrared multiple photon dissociation spectroscopy and density functional theory investigations.

Correction for 'Zn and Cd cationized serine complexes: infrared multiple photon dissociation spectroscopy and density functional theory investigations' by Rebecca A. Coates et al., Phys.

Experimental and theoretical investigations of infrared multiple photon dissociation spectra of glutamic acid complexes with Zn and Cd.

Complexes of glutamic acid (Glu) cationized with Zn and Cd were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free electron laser. Complexes of deprotonated Glu with Zn, [Zn(Glu-H)ACN] (where ACN = acetonitrile, CHCN), and intact Glu with CdCl, CdCl(Glu) were formed. Notably, photodissociation induces Glu fragmentation rather than ACN loss in the Zn complex.

Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Asparagine Complexes with Zn and Cd and Their Deamidation Processes.

Complexes of asparagine (Asn) cationized with Zn and Cd were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free electron laser. Electrospray ionization yielded complexes of deprotonated Asn with Zn, [Zn(Asn-H)], and intact Asn with CdCl, CdCl(Asn). Series of low energy conformers for each complex were found using quantum chemical calculations in order to identify the structures formed experimentally.

Zn(2+) and Cd(2+) cationized serine complexes: infrared multiple photon dissociation spectroscopy and density functional theory investigations.

The gas-phase structures of zinc and cadmium dications bound to serine (Ser) are investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using the free electron laser FELIX, in combination with ab initio calculations. To identify the structures of the experimentally observed species, [Zn(Ser-H)CH3CN](+) and CdCl(+)(Ser), the measured action spectra are compared to linear absorption spectra calculated at the B3LYP/6-311+G(d,p) level for Zn(2+) containing complexes and B3LYP/def2-TZVP levels for Cd(2+) containing complexes. Good agreement between the observed IRMPD spectra and the predicted spectra allows identification of the isomers present.

Thermodynamics and Mechanisms of Protonated Asparaginyl-Glycine Decomposition.

Deamidation at asparagine residues, a spontaneous post-translational modification in proteins, plays a significant role in various biological processes and degenerative diseases. In the current work, we present a full description of the deamidation process as well as other key fragmentations (dehydration, peptide bond cleavage, and loss of 2 NH3) from protonated asparaginyl-glycine, H(+)(AsnGly), by studying its kinetic energy dependent collision-induced dissociation (CID) with Xe using a guided ion beam tandem mass spectrometer. These results are compared with those for sustained off-resonance irradiation (SORI)-CID of H(+)(AsnGly) with Ar in a Fourier transform ion cyclotron resonance mass spectrometer.

Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Glutamine Complexes with Zn(2+) and Cd(2.).

Complexes of glutamine (Gln) cationized with Zn(2+) and Cd(2+) were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free-electron laser. Electrospray ionization yielded complexes of deprotonated Gln with Zn(2+), [Zn(Gln-H)](+), and intact Gln with CdCl(+), CdCl(+)(Gln). For each complex, the spectra obtained were compared with those for low-energy conformers found using quantum chemical calculations to identify the structures present experimentally.

Structural characterization of gas-phase cysteine and cysteine methyl ester complexes with zinc and cadmium dications by infrared multiple photon dissociation spectroscopy.

Structural characterization of gas-phase ions of cysteine (Cys) and cysteine methyl ester (CysOMe) complexed to zinc and cadmium is investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using a free electron laser in combination with density functional theory calculations. IRMPD spectra are measured for [Zn(Cys-H)](+), [Cd(Cys-H)](+), [Zn(CysOMe-H)](+), [Cd(CysOMe-H)](+) and CdCl(+)(CysOMe) and are accompanied by quantum mechanical calculations of the predicted linear absorption spectra at the B3LYP/6-311+G(d,p) (Zn(2+) complexes) and B3LYP/def2TZVP levels (Cd(2+) complexes). On the basis of these experiments and calculations, the conformation that best reproduces the IRMPD spectra for the complexes of the deprotonated amino acids, [M(Cys-H)](+) and [M(CysOMe-H)](+), is a charge-solvated (CS) tridentate structure where the metal dication binds to the amine and carbonyl groups of the amino acid backbone and the deprotonated sulfur atom of the side chain, [N,CO,S(-)].