scholarly journals Intrinsic fluorescence in non-aromatic peptide structures is induced by collective vibrations, charge reorganisation and short hydrogen bonds, as shown in a new glutamine-related structure

2020 ◽  
Author(s):  
Amberley D. Stephens ◽  
Muhammad Nawaz Qaisrani ◽  
Michael T. Ruggiero ◽  
Saul T.E. Jones ◽  
Emiliano Poli ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Optical Activity ◽  
Stokes Shift ◽  
Model System ◽  
Optically Active ◽  
Single Amino Acid ◽  
Broad Absorption ◽  
Active Structures ◽  
Collective Vibrations ◽  
Short Hydrogen Bonds

AbstractDisentangling the origin of the optical activity of non-aromatic proteins is challenging due to their size and thus their high computational requisites. Here we show, in a much smaller model system, that the single amino acid glutamine undergoes a chemical transformation leading to an unreported glutamine-like structure which has a similar broad absorption spectrum reported previously for non-aromatic proteins. We further show computationally that the optical activity of the glutamine-like structure is directly coupled to short-hydrogen bonds, but also displays charge and vibrational fluctuations, the latter of which are also present in less optically active structures such as in L-glutamine. Since experimentally the glutamine-like structure is the brightest structure, we conclude that short-hydrogen bonds are the ones responsible for the large Stokes shift observed in optically active non-aromatic proteins.

scholarly journals Short hydrogen bonds enhance nonaromatic protein-related fluorescence

2021 ◽  
Vol 118 (21) ◽  
pp. e2020389118
Author(s):  
Amberley D. Stephens ◽  
Muhammad Nawaz Qaisrani ◽  
Michael T. Ruggiero ◽  
Gonzalo Díaz Mirón ◽  
Uriel N. Morzan ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Transition Probabilities ◽  
Ab Initio Molecular Dynamics ◽  
Single Amino Acid ◽  
Hydrogen Bond Networks ◽  
Short Hydrogen Bond ◽  
Photoactive Materials ◽  
Dynamics Simulations ◽  
Short Hydrogen Bonds

Fluorescence in biological systems is usually associated with the presence of aromatic groups. Here, by employing a combined experimental and computational approach, we show that specific hydrogen bond networks can significantly affect fluorescence. In particular, we reveal that the single amino acid L-glutamine, by undergoing a chemical transformation leading to the formation of a short hydrogen bond, displays optical properties that are significantly enhanced compared with L-glutamine itself. Ab initio molecular dynamics simulations highlight that these short hydrogen bonds prevent the appearance of a conical intersection between the excited and the ground states and thereby significantly decrease nonradiative transition probabilities. Our findings open the door to the design of new photoactive materials with biophotonic applications.

Relevance of hydrogen bonded associates on the transport properties and nanoscale dynamics of liquid and supercooled 2-propanol

2021 ◽  
Author(s):  
Yanqin Zhai ◽  
Peng Luo ◽  
Michihiro Nagao ◽  
Kenji Nakajima ◽  
Tatsuya Kikuchi ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Transport Properties ◽  
Structural Relaxation ◽  
Model System ◽  
Mesoscale Structures ◽  
Nanoscale Dynamics ◽  
Hydrogen Bonded

2-propanol was investigated, in both the liquid and supercooled states, as a model system to study how hydrogen bonds affect the structural relaxation and the dynamics of mesoscale structures, of...

On the syntheses and the optical properties of optically active 2-pyrazoline compounds

1979 ◽  
Vol 57 (3) ◽  
pp. 360-366 ◽  
Author(s):  
Makoto Mukai ◽  
Takashi Miura ◽  
Masahiro Nanbu ◽  
Toshinobu Yoneda ◽  
Yohji Shindo
Keyword(s):  
Optical Properties ◽  
Optical Activity ◽  
Optically Active ◽  
Spectroscopic Techniques ◽  
Considerable Influence ◽  
Pyrazoline Ring

Optically active 2-pyrazolines were synthesized and their optical properties were studied using various spectroscopic techniques to investigate the effects of substituents at the 3 and 5 positions of the 2-pyrazoline ring on their optical activity. It was found that in the case of 5-substituted-1,3-diphenyl-2-pyrazoline derivatives, the substituent at the 5 position has considerable influence on the optical activity, whereas in 3-substituted-1,5-diphenyl-2-pyrazoline derivatives, the substituent at the 3 position has no such influence.

Structure of ammonium hydrogen succinate above and below the phase transition around 170K

1996 ◽  
Vol 52 (2) ◽  
pp. 323-327 ◽  
Author(s):  
A. Hirano ◽  
Y. Kubozono ◽  
H. Maeda ◽  
H. Ishida ◽  
S. Kashino
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Order Phase Transition ◽  
Space Group ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
Significant Change ◽  
Short Hydrogen Bonds ◽  
Second Order Phase Transition

For crystals of ammonium hydrogen succinate it is known that the space group is P{\bar 1} with Z = 2 at 293 K and the second-order phase transition occurs around 170 K. X-ray crystal structure analyses above and below 170 K have been carried out in order to study the change in mode of short hydrogen bonds between the hydrogen succinate ions. The space group was determined to be P{\bar 1} at 150 and 190 K by structure analysis. No ordering of the H-atom positions in the short hydrogen bonds occurs by the phase transition. The hydrogen bonds show a decrease in the O...O distances with a decrease in temperature from 290 to 190 K, but no significant change in the geometries between 190 and 150 K. Disorder of the NH4 + ion is not observed at 297, 190 and 150 K. Significant change through the phase transition is found only in the geometry of one of the N—H...O hydrogen bonds between ammonium and hydrogen succinate ions.

scholarly journals Enhanced gyrotropic birefringence and natural optical activity on electromagnon resonance in a helimagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Iguchi ◽  
R. Masuda ◽  
S. Seki ◽  
Y. Tokura ◽  
Y. Takahashi
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Optical Activity ◽  
Optical Rotation ◽  
Magnetoelectric Coupling ◽  
Optically Active ◽  
Crystalline Solid ◽  
Spin Order ◽  
Active Devices ◽  
Principal Axes

AbstractSpontaneous symmetry breaking in crystalline solid often produces exotic nonreciprocal phenomena. As one such example, the unconventional optical rotation with nonreciprocity, which is termed gyrotropic birefringence, is expected to emerge from the magnetoelectric coupling. However, the fundamental nature of gyrotropic birefringence remains to be examined. Here w`e demonstrate the gyrotropic birefringence enhanced by the dynamical magnetoelectric coupling on the electrically active magnon resonance, i.e. electromagnon, in a multiferroic helimagnet. The helical spin order having both polarity and chirality is found to cause the giant gyrotropic birefringence in addition to the conventional gyrotropy, i.e. natural optical activity. It is demonstrated that the optical rotation of gyrotropic birefringence can be viewed as the nonreciprocal rotation of the optical principal axes, while the crystallographic and magnetic anisotropies are intact. The independent control of the nonreciprocal linear (gyrotropic birefringence) and circular (natural optical activity) birefringence/dichroism paves a way for the optically active devices.

scholarly journals 1,4-Dimethylenespiropentane: A Unique Model System for Studying Fermi Resonance in Raman Optical Activity

ChemPhysChem ◽  
2007 ◽  
Vol 8 (8) ◽  
pp. 1161-1169 ◽  
Author(s):  
Werner Hug ◽  
Jacques Haesler ◽  
Sergei I. Kozhushkov ◽  
Armin de Meijere
Keyword(s):  
Optical Activity ◽  
Model System ◽  
Fermi Resonance ◽  
Raman Optical Activity ◽  
Unique Model

scholarly journals Short hydrogen bonds in the catalytic mechanism of serine proteases

2008 ◽  
Vol 73 (4) ◽  
pp. 393-403 ◽  
Author(s):  
Vladimir Leskovac ◽  
Svetlana Trivic ◽  
Draginja Pericin ◽  
Mira Popovic ◽  
Julijan Kandrac
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Active Site ◽  
Serine Proteases ◽  
Active Sites ◽  
Catalytic Mechanism ◽  
Data Bank ◽  
Ground State Structure ◽  
Low Barrier Hydrogen Bonds ◽  
Short Hydrogen Bonds

The survey of crystallographic data from the Protein Data Bank for 37 structures of trypsin and other serine proteases at a resolution of 0.78-1.28 ? revealed the presence of hydrogen bonds in the active site of the enzymes, which are formed between the catalytic histidine and aspartate residues and are on average 2.7 ? long. This is the typical bond length for normal hydrogen bonds. The geometric properties of the hydrogen bonds in the active site indicate that the H atom is not centered between the heteroatoms of the catalytic histidine and aspartate residues in the active site. Taken together, these findings exclude the possibility that short "low-barrier" hydrogen bonds are formed in the ground state structure of the active sites examined in this work. Some time ago, it was suggested by Cleland that the "low-barrier hydrogen bond" hypothesis is operative in the catalytic mechanism of serine proteases, and requires the presence of short hydrogen bonds around 2.4 ? long in the active site, with the H atom centered between the catalytic heteroatoms. The conclusions drawn from this work do not exclude the validity of the "low-barrier hydrogen bond" hypothesis at all, but they merely do not support it in this particular case, with this particular class of enzymes.

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