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Title: Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn

Authors:
ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1349951
Grant/Contract Number:
FG02-00ER15105
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 15; Related Information: CHORUS Timestamp: 2018-03-29 04:25:09; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English

Citation Formats

DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., and Zwier, Timothy S. Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn. United States: N. p., 2017. Web. doi:10.1021/jacs.7b01315.
DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., & Zwier, Timothy S. Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn. United States. doi:10.1021/jacs.7b01315.
DeBlase, Andrew F., Harrilal, Christopher P., Lawler, John T., Burke, Nicole L., McLuckey, Scott A., and Zwier, Timothy S. Thu . "Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn". United States. doi:10.1021/jacs.7b01315.
@article{osti_1349951,
title = {Conformation-Specific Infrared and Ultraviolet Spectroscopy of Cold [YAPAA+H] + and [YGPAA+H] + Ions: A Stereochemical “Twist” on the β-Hairpin Turn},
author = {DeBlase, Andrew F. and Harrilal, Christopher P. and Lawler, John T. and Burke, Nicole L. and McLuckey, Scott A. and Zwier, Timothy S.},
abstractNote = {},
doi = {10.1021/jacs.7b01315},
journal = {Journal of the American Chemical Society},
number = 15,
volume = 139,
place = {United States},
year = {Thu Apr 06 00:00:00 EDT 2017},
month = {Thu Apr 06 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/jacs.7b01315

Citation Metrics:
Cited by: 1work
Citation information provided by
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  • We present the spectroscopy and photofragmentation dynamics of two isomeric protonated dipeptides, H{sup +}AlaTyr and H{sup +}TyrAla, in a cold ion trap. By a combination of infrared-ultraviolet double resonance experiments and density functional theory calculations, we establish the conformations present at low temperature. Interaction of the charge at the N-terminus with the carbonyl group and the tyrosine {pi}-cloud seems to be critical in stabilizing the low-energy conformations. H{sup +}AlaTyr has the flexibility to allow a stronger interaction between the charge and the aromatic ring than in H{sup +}TyrAla, and this interaction may be responsible for many of the differences wemore » observe in the former: a significant redshift in the ultraviolet spectrum, a much larger photofragmentation yield, fewer stable conformations, and the absence of fragmentation in excited electronic states.« less
  • Highlights: • Bordetella pertussis adenylate cyclase toxin modulates bi-lobal structure of CaM. • The structure and stability of the complex rely on intermolecular associations. • A novel mode of CaM-dependent activation of the adenylate cyclase toxin is proposed. - Abstract: Bordetella pertussis, causative agent of whooping cough, produces an adenylate cyclase toxin (CyaA) that is an important virulence factor. In the host cell, the adenylate cyclase domain of CyaA (CyaA-ACD) is activated upon association with calmodulin (CaM), an EF-hand protein comprised of N- and C-lobes (N-CaM and C-CaM, respectively) connected by a flexible tether. Maximal CyaA-ACD activation is achieved throughmore » its binding to both lobes of intact CaM, but the structural mechanisms remain unclear. No high-resolution structure of the intact CaM/CyaA-ACD complex is available, but crystal structures of isolated C-CaM bound to CyaA-ACD shed light on the molecular mechanism by which this lobe activates the toxin. Previous studies using molecular modeling, biochemical, and biophysical experiments demonstrate that CyaA-ACD’s β-hairpin participates in site-specific interactions with N-CaM. In this study, we utilize nuclear magnetic resonance (NMR) spectroscopy to probe the molecular association between intact CaM and CyaA-ACD. Our results indicate binding of CyaA-ACD to CaM induces large conformational perturbations mapping to C-CaM, while substantially smaller structural changes are localized primarily to helices I, II, and IV, and the metal-binding sites in N-CaM. Site-specific mutations in CyaA-ACD’s β-hairpin structurally modulate N-CaM, resulting in conformational perturbations in metal binding sites I and II, while no significant structural modifications are observed in C-CaM. Moreover, dynamic light scattering (DLS) analysis reveals that mutation of the β-hairpin results in a decreased hydrodynamic radius (R{sub h}) and reduced thermal stability in the mutant complex. Taken together, our data provide new structural insights into the β-hairpin’s role in stabilizing interactions between CyaA-ACD and N-CaM.« less
  • M{sup +}(H{sub 2}O){sub n} and M{sup +}(H{sub 2}O){sub n}{center_dot}Ar ions (M=Cu and Ag) are studied for exploring coordination and solvation structures of noble-metal ions. These species are produced in a laser-vaporization cluster source and probed with infrared (IR) photodissociation spectroscopy in the OH-stretch region using a triple quadrupole mass spectrometer. Density functional theory calculations are also carried out for analyzing the experimental IR spectra. Partially resolved rotational structure observed in the spectrum of Ag{sup +}(H{sub 2}O){sub 1}{center_dot}Ar indicates that the complex is quasilinear in an Ar-Ag{sup +}-O configuration with the H atoms symmetrically displaced off axis. The spectra of themore » Ar-tagged M{sup +}(H{sub 2}O){sub 2} are consistent with twofold coordination with a linear O-M{sup +}-O arrangement for these ions, which is stabilized by the s-d hybridization in M{sup +}. Hydrogen bonding between H{sub 2}O molecules is absent in Ag{sup +}(H{sub 2}O){sub 3}{center_dot}Ar but detected in Cu{sup +}(H{sub 2}O){sub 3}{center_dot}Ar through characteristic changes in the position and intensity of the OH-stretch transitions. The third H{sub 2}O attaches directly to Ag{sup +} in a tricoordinated form, while it occupies a hydrogen-bonding site in the second shell of the dicoordinated Cu{sup +}. The preference of the tricoordination is attributable to the inefficient 5s-4d hybridization in Ag{sup +}, in contrast to the extensive 4s-3d hybridization in Cu{sup +} which retains the dicoordination. This is most likely because the s-d energy gap of Ag{sup +} is much larger than that of Cu{sup +}. The fourth H{sub 2}O occupies the second shells of the tricoordinated Ag{sup +} and the dicoordinated Cu{sup +}, as extensive hydrogen bonding is observed in M{sup +}(H{sub 2}O){sub 4}{center_dot}Ar. Interestingly, the Ag{sup +}(H{sub 2}O){sub 4}{center_dot}Ar ions adopt not only the tricoordinated form but also the dicoordinated forms, which are absent in Ag{sup +}(H{sub 2}O){sub 3}{center_dot}Ar but revived at n=4. Size dependent variations in the spectra of Cu{sup +}(H{sub 2}O){sub n} for n=5-7 provide evidence for the completion of the second shell at n=6, where the dicoordinated Cu{sup +}(H{sub 2}O){sub 2} subunit is surrounded by four H{sub 2}O molecules. The gas-phase coordination number of Cu{sup +} is 2 and the resulting linearly coordinated structure acts as the core of further solvation processes.« less
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  • The vibrational spectra of the clusters H/sup +//sub 3/(H/sub 2/)/sub n/ were observed near 4000 cm/sup -1/ by vibrational predissociation spectroscopy. Spectra of mass-selected clusters were obtained by trapping the ions in a radio frequency ion trap, exciting vibrational transitions of the cluster ions to predissociating levels, and detecting the fragment ions with a mass spectrometer. Low resolution bands of the solvent H/sub 2/ stretches were observed for the clusters of one to six H/sub 2/ coordinated to an H/sup +//sub 3/ ion. The red shift of these vibrations relative to the monomer H/sub 2/ frequency supported the model ofmore » H/sup +//sub 9/ as an H/sup +//sub 3/ with a complete inner solvation shell of three H/sub 2/, one bound to each corner of the ion. Two additional bands of H/sup +//sub 5/ were observed, one assigned as the H/sup +//sub 3/ symmetric stretch, and the other as a combination or overtone band. High-resolution scans (0.5 and 0.08 cm/sup -1/) of H/sup +//sub n/, n = 5, 7, and 9 yielded no observable rotational structure, a result of either spectral congestion or rapid cluster dissociation. The band contour of the H/sup +//sub 5/ band changed upon cooling the internal degrees of freedom, but the peaks remained featureless. The observed frequencies of H/sup +//sub 7/ and H/sup +//sub 9/ agreed well with ab initio predictions, but those of H/sup +//sub 5/ did not. This deviation is discussed in terms of the large expected anharmonicity of the proton bound dimer H/sup +//sub 5/.« less