Oxygen K-shell spectroscopy of isolated progressively solvated peptide

2020 ◽  
Vol 22 (23) ◽  
pp. 12909-12917
Author(s):  
Aleksandar R. Milosavljević ◽  
Kari Jänkälä ◽  
Miloš Lj. Ranković ◽  
Francis Canon ◽  
John Bozek ◽  
...  
Keyword(s):  
Solvation Shell ◽  
Core Excitation ◽  
Peptide Backbone ◽  
X Ray ◽  
Peptide Core

X-ray spectroscopy of an isolated controllably hydrated peptide: core excitation of the first solvation shell enhances peptide backbone fragmentation.

scholarly journals Probing calcium solvation by XAS, MD and DFT calculations

RSC Advances ◽  
2020 ◽  
Vol 10 (46) ◽  
pp. 27315-27321 ◽  
Author(s):  
Feipeng Yang ◽  
Yi-Sheng Liu ◽  
Xuefei Feng ◽  
Kun Qian ◽  
Li Cheng Kao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Md Simulations ◽  
Solvation Shell ◽  
Shell Structures ◽  
X Ray

The solvation shell structures of Ca2+ in solutions are probed by calcium L-edge soft X-ray XAS and DFT/MD simulations.

scholarly journals Integrating solvation shell structure in experimentally driven molecular dynamics using x-ray solution scattering data

2020 ◽  
Vol 152 (20) ◽  
pp. 204115 ◽  
Author(s):  
Darren J. Hsu ◽  
Denis Leshchev ◽  
Irina Kosheleva ◽  
Kevin L. Kohlstedt ◽  
Lin X. Chen
Keyword(s):  
Molecular Dynamics ◽  
Shell Structure ◽  
Solvation Shell ◽  
Scattering Data ◽  
X Ray

Probing symmetry breaking upon core excitation with resonant x-ray fluorescence

1995 ◽  
Vol 52 (5) ◽  
pp. 3572-3576 ◽  
Author(s):  
Per Skytt ◽  
Jinghua Guo ◽  
Nial Wassdahl ◽  
Joseph Nordgren ◽  
Yi Luo ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Core Excitation ◽  
X Ray

Interlayer states of LiC6 investigated by inelastic X-ray scattering spectroscopy (IXSS) using Li-core excitation

1991 ◽  
Vol 79 (8) ◽  
pp. 657-660 ◽  
Author(s):  
W. Schülke ◽  
K.-J. Gabriel ◽  
A. Berthold ◽  
H. Schulte-Schrepping
Keyword(s):  
Core Excitation ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Solvation dynamics monitored by combined X-ray spectroscopies and scattering: photoinduced spin transition in aqueous [Fe(bpy)3]2+

2014 ◽  
Vol 171 ◽  
pp. 169-178 ◽  
Author(s):  
C. Bressler ◽  
W. Gawelda ◽  
A. Galler ◽  
M. M. Nielsen ◽  
V. Sundström ◽  
...  
Keyword(s):  
Time Resolution ◽  
Time Scale ◽  
Spin Transition ◽  
Solvation Shell ◽  
Precise Determination ◽  
Heating Process ◽  
Solvation Dynamics ◽  
X Ray ◽  
Structure Changes

We have studied the photoinduced low spin (LS) to high spin (HS) conversion of aqueous Fe(bpy)3 with pulse-limited time resolution. In a combined setup permitting simultaneous X-ray diffuse scattering (XDS) and spectroscopic measurements at a MHz repetition rate we have unraveled the interplay between intramolecular dynamics and the intermolecular caging solvent response with 100 ps time resolution. On this time scale the ultrafast spin transition including intramolecular geometric structure changes as well as the concomitant bulk solvent heating process due to energy dissipation from the excited HS molecule are long completed. The heating is nevertheless observed to further increase due to the excess energy between HS and LS states released on a subnanosecond time scale. The analysis of the spectroscopic data allows precise determination of the excited population which efficiently reduces the number of free parameters in the XDS analysis, and both combined permit extraction of information about the structural dynamics of the first solvation shell.

scholarly journals Imaging of transition charge densities involving carbon core excitations by all X-ray sum-frequency generation

2019 ◽  
Vol 377 (2145) ◽  
pp. 20170470 ◽  
Author(s):  
Daeheum Cho ◽  
Jérémy R. Rouxel ◽  
Markus Kowalewski ◽  
JinYong Lee ◽  
Shaul Mukamel
Keyword(s):  
Charge Density ◽  
Density Functional ◽  
Sum Frequency Generation ◽  
X Rays ◽  
Core Excitation ◽  
X Ray ◽  
Sum Frequency ◽  
Electron Density Matrix ◽  
Frequency Generation ◽  
Core Excitations

X-ray diffraction signals from the time-evolving molecular charge density induced by selective core excitation of chemically inequivalent carbon atoms are calculated. A narrowband X-ray pulse selectively excites the carbon K-edge of the –CH 3 or –CH 2 F groups in fluoroethane (CH 3 –CH 2 F). Each excitation creates a distinct core coherence which depends on the character of the electronic transition. Direct propagation of the reduced single-electron density matrix, using real-time time-dependent density functional theory, provides the time-evolving charge density following interactions with external fields. The interplay between partially filled valence molecular orbitals upon core excitation induces characteristic femtosecond charge migration which depends on the core–valence coherence, and is monitored by the sum-frequency generation diffraction signal. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

Inner-shell excitation studies of conducting organic polymers: selenophene, 3-methyl selenophene, and their polymers

1989 ◽  
Vol 67 (11) ◽  
pp. 1819-1827 ◽  
Author(s):  
A. P. Hitchcock ◽  
G. Tourillon ◽  
W. Braun
Keyword(s):  
Electrical Conductivity ◽  
Polymeric Chain ◽  
Core Excitation ◽  
Structural Units ◽  
X Ray ◽  
Methyl Substitution ◽  
Electrically Conducting ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Electron Energy Loss Spectra

Inner-shell electron energy loss spectra (ISEELS) of gaseous selenophene and 3-methylselenophene in the regions of Se 3d, Se 3p, Se 3s, and C 1s are presented and analyzed. The ISEELS spectra are compared to the C 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of the corresponding polymers deposited electrochemically onto Pt, both with and without doping, to form the electrically conducting state. Methyl substitution at the 3-position of the selenophene ring is found to have little effect on the intensity of the C 1s → π* transition, suggesting that the π manifold is relatively unaffected. The C 1s NEXAFS of thin polyselenophene and poly-3-methylselenophene films confirms that (1) the polymeric chain is composed of the same structural units as the monomers and (2) doping enhances electrical conductivity via a narrowing of the π–π* band gap. Keywords: core excitation, ISEELS, NEXAFS, conducting polymers.

scholarly journals Conformational Preferences and Antiproliferative Activity of Peptidomimetics Containing Methyl 1′-Aminoferrocene-1-carboxylate and Turn-Forming Homo- and Heterochiral Pro-Ala Motifs

2021 ◽  
Vol 22 (24) ◽  
pp. 13532
Author(s):  
Monika Kovačević ◽  
Mojca Čakić Semenčić ◽  
Kristina Radošević ◽  
Krešimir Molčanov ◽  
Sunčica Roca ◽  
...  
Keyword(s):  
Biological Function ◽  
Clonogenic Assay ◽  
Conformational Flexibility ◽  
Peptide Backbone ◽  
X Ray ◽  
Structural Modifications ◽  
Conformational Preferences ◽  
Biological Potential ◽  
Viability Study ◽  
Natural Peptides

The concept of peptidomimetics is based on structural modifications of natural peptides that aim not only to mimic their 3D shape and biological function, but also to reduce their limitations. The peptidomimetic approach is used in medicinal chemistry to develop drug-like compounds that are more active and selective than natural peptides and have fewer side effects. One of the synthetic strategies for obtaining peptidomimetics involves mimicking peptide α-helices, β-sheets or turns. Turns are usually located on the protein surface where they interact with various receptors and are therefore involved in numerous biological events. Among the various synthetic tools for turn mimetic design reported so far, our group uses an approach based on the insertion of different ferrocene templates into the peptide backbone that both induce turn formation and reduce conformational flexibility. Here, we conjugated methyl 1′-aminoferrocene-carboxylate with homo- and heterochiral Pro-Ala dipeptides to investigate the turn formation potential and antiproliferative properties of the resulting peptidomimetics 2–5. Detailed spectroscopic (IR, NMR, CD), X-ray and DFT studies showed that the heterochiral conjugates 2 and 3 were more suitable for the formation of β-turns. Cell viability study, clonogenic assay and cell death analysis showed the highest biological potential of homochiral peptide 4.

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