0000000001320377
AUTHOR
Ali Hassanali
showing 7 related works from this author
Intrinsic fluorescence in non-aromatic peptide structures is induced by collective vibrations, charge reorganisation and short hydrogen bonds, as sho…
2020
Abstract Disentangling 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…
Short hydrogen bonds enhance nonaromatic protein-related fluorescence
2021
Significance Intrinsic fluorescence of nonaromatic amino acids is a puzzling phenomenon with an enormous potential in biophotonic applications. The physical origins of this effect, however, remain elusive. Herein, we demonstrate how specific hydrogen bond networks can modulate fluorescence. We highlight the key role played by short hydrogen bonds, present in the protein structure, on the ensuing fluorescence. We provide detailed experimental and molecular evidence to explain these unusual nonaromatic optical properties. Our findings should benefit the design of novel optically active biomaterials for applications in biosensing and imaging.
Short hydrogen bonds enhance non-aromatic protein-related fluorescence
2020
AbstractFluorescence in biological systems is usually associated with the presence of aromatic groups. Here, we show that specific hydrogen bonding networks can significantly affect fluorescence employing a combined experimental and computational approach. 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 to 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 signific…
Structure and Dynamics of the Instantaneous Water/Vapor Interface Revisited by Path-Integral and Ab Initio Molecular Dynamics Simulations
2015
The structure and dynamics of the water/vapor interface is revisited by means of path-integral and second-generation Car-Parrinello ab-initio molecular dynamics simulations in conjunction with an instantaneous surface definition [A. P. Willard and D. Chandler, J. Phys. Chem. B 114, 1954 (2010)]. In agreement with previous studies, we find that one of the OH bonds of the water molecules in the topmost layer is pointing out of the water into the vapor phase, while the orientation of the underlying layer is reversed. Therebetween, an additional water layer is detected, where the molecules are aligned parallel to the instantaneous water surface.
Proton transfer through the water gossamer.
2013
International audience; The diffusion of protons through water is understood within the framework of the Grotthuss mechanism, which requires that they undergo structural diffusion in a stepwise manner throughout the water network. Despite long study, this picture oversimplifies and neglects the complexity of the supramolecular structure of water. We use first-principles simulations and demonstrate that the currently accepted picture of proton diffusion is in need of revision. We show that proton and hydroxide diffusion occurs through periods of intense activity involving concerted proton hopping followed by periods of rest. The picture that emerges is that proton transfer is a multiscale an…
CCDC 1981551: Experimental Crystal Structure Determination
2021
Related Article: Amberley D. Stephens, Muhammad Nawaz Qaisrani, Michael T. Ruggiero, Gonzalo Díaz Mirón, Uriel N. Morzan, Mariano C. González Lebrero, Saul T. E. Jones, Emiliano Poli, Andrew D. Bond, Philippa J. Woodhams, Elyse M. Kleist, Luca Grisanti, Ralph Gebauer, J. Axel Zeitler, Dan Credgington, Ali Hassanali, Gabriele S. Kaminski Schierle|2021|Proc.Nat.Acad.Sci.USA|118|e2020389118|doi:10.1073/pnas.2020389118
Research data supporting 'Short hydrogen bonds enhance nonaromatic protein-related fluorescence'
2021
Raw data for experimental figures. Files contain .cif (crystallographic information file) for XRD data of the L-pyro-amm structure. .xlsx file containing spectra for absorption of L-glutamine, L-pyroglutamine and L-pyro-amm. .xlsx file contains spectra for fluorescence excitation and emission collected over 8 days for L-glutamine conversion to L-pyro-amm.