This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling between them. We found that the key to this strong coupling is the existence of a fragile-to-strong dynamic crossover (FSC) phenomenon occurring at around TL = 225±5 K in the hydration water. On lowering of the temperature toward FSC, the structure of hydration water makes a transition from predominantly the high density form (HDL), a more fluid state, to predominantly the low density form (LDL), a less fluid state, derived from the existence of a liquid–liquid critical point at an elevated pressure. We show experimentally that this sudden switch in the mobility of hydration water on Lysozyme, B-DNA and RNA triggers the dynamic transition, at a temperature TD = 220 K, for these biopolymers. In the glassy state, below TD, the biopolymers lose their vital conformational flexibility resulting in a substantial diminishing of their biological functions. We also performed molecular dynamics (MD) simulations on a realistic model of hydrated lysozyme powder, which confirms the existence of the FSC and the hydration level dependence of the FSC temperature. Furthermore, we show a striking feature in the short time relaxation (β-relaxation) of protein dynamics, which is the logarithmic decay spanning 3 decades (from ps to ns). The long time α-relaxation shows instead a diffusive behavior, which supports the liquid-like motions of protein constituents. We then discuss our recent high-resolution X-ray inelastic scattering studies of globular proteins, Lysozyme and Bovine Serum Albumin. We were able to measure the dispersion relations of collective, intra-protein phonon-like excitations in these proteins for the first time. We found that the phonon energies show a marked softening and at the same time their population increases substantially in a certain wave vector range when temperature crosses over the TD. Thus the increase of biological activities above TD has positive correlation with activation of slower and large amplitude collective motions of a protein.

Sow-Hsin Chen

Marco Lagi

Xiang-qiang Chu

Yang Zhang

Chansoo Kim

Antonio Faraone

Emiliano Fratini

Piero Baglioni

Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

It is widely accepted that FTIR spectroscopy has a huge potential in cancer diagnosis. However further work is required to bring this technique into pathology departments. One of the areas where big efforts will be required is the development of cell spectra databases to be used in the diagnosis of cancer. Presently, unstained cytology and tissue samples are studied with FTIR spectroscopy. However, it is not always possible to identify in unstained samples the types of cells present. In order to achieve this, samples need staining after FTIR spectra have been obtained. We have recently shown it is possible to obtain FTIR spectra of stained cells using a synchrotron source (10.1038/labinvest.2010.8). This allows recording FTIR spectra from cells already characterized by pathologists. In order to further this work, we have now obtained FTIR spectra from stained (Papanicolau or Haematoxylin &amp; Eosin) single cells using a benchtop spectrometer. This would be the logical step towards a clinical application in cancer diagnosis. The data here presented show that staining caused a decreased intensity of the peaks at 2920 cm−1 and 2850 cm−1, and the appearance of stronger peaks at 1374 cm−1 and 1040 cm−1. The clinical applications are discussed.

Jacek K. Pijanka

Nicholas Stone

Gianfelice Cinque

Ying Yang

Achim Kohler

Katia Wehbe

Mark Frogley

Gary Parkes

Joanne Parkes

Paul Dumas

Christophe Sandt

Daniel G. van Pittius

Gillian Douce

Ganesh D. Sockalingum

Josep Sulé-Suso

FTIR microspectroscopy of stained cells and tissues. Application in cancer diagnosis

We have developed a Raman microspectroscopy system optimised for studying supported lipid bilayers (SLB). This system combines the benefits of Raman spectroscopy with the high spatial resolution of confocal microscopy. Furthermore, the additional incorporation of an atomic force microscope (AFM) makes it possible to directly correlate chemical information with spatial features of samples at the nanoscale. We focus on the limits of this system for detecting a single SLB and imaging its microdomains, and employ surface-enhanced Raman spectroscopy (SERS) to improve the sensitivity achieved with Raman microspectroscopy.

Claire S. Sweetenham

Ioan Notingher

Raman spectroscopy methods for detecting and imaging supported lipid bilayers

Human serum albumin provides the transport of long-chain fatty acids in the blood through three high-affinity and four low-affinity binding sites. Molecular dynamics simulations have been performed to investigate the anchoring of palmitic acid molecules to the protein. In the site with the highest affinity, Site 5, the key residue Lys525 not only binds the head-group of the palmitate ion by electrostatic interactions with its charged terminal group, but it also accommodates the first portion of the lipid chain by non-electrostatic interactions with the rest of its sidechain. The flexibility of Lys525, and in particular of the dihedral angle &#x3c7;3, is suggested to account for a number of spectroscopic properties observed in correspondence with the entrance of the hydrophobic pocket constituting Site 5.

Bruno Rizzuti

Manuela Pantusa

Rita Guzzi

The role of Lys525 on the head-group anchoring of fatty acids in the highest affinity binding site of albumin

The possibility of interaction between linker histone H1 and non-histone chromatin protein HMGB1 was studied by intrinsic UV-fluorescence, far and near-UV CD and light scattering. The obtained data allow us to assume that the increase of histone H1 content in the HMGB1 solutions in a low ionic strength is accompanied by the destruction of HMGB1 associates. The interaction between proteins causes the increase of ordered regions in the protein molecules and the minor changes in their tertiary structure.

Alexander V. Fonin

Olga V. Stepanenko

Irina M. Kuznetsova

Konstantin K. Turoverov

Elena I. Kostyleva

Vladimir I. Vorobyev

Interaction between linker histone H1 and non-histone chromatin protein HMGB1

Benzthiazole dye thioflavin T (ThT) is widely used for studying amyloid fibrils structure and formation. Nevertheless, till now there is no common opinion concerning molecular mechanisms of ThT binding to amyloid fibrils and the reasons of dramatic increase of its fluorescence quantum yield on incorporation into amyloid fibrils. Our data prove that ThT molecules incorporate in amyloid fibrils in monomeric form and there is no ground to suppose the formation of ThT dimers, eximers, or micelles. It was shown that the increase of quantum yield of ThT incorporated in amyloid fibrils is caused by restriction of benzthiazole and aminobenzene rings torsion fluctuations about each other.

A. I. Sulatskaya

K. K. Turoverov

I. M. Kuznetsova

Spectral properties and factors determining high quantum yield of thioflavin T incorporated in amyloid fibrils

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Journal of Spectroscopy publishes research into the theory and application of spectroscopy across all disciplines, including biology, chemistry, engineering, earth sciences, medicine, materials science, physics, and space science.

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Chief Editor&nbsp;Dr Daniel Cozzolino&nbsp;is based at the University of Queensland, Australia. His research focuses on the developments of chemometric and spectroscopic methods for use in agriculture and food applications.

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