The investigations of the interaction between phospholipid bilayer and short-chain alcohols are relevant for the potential of lipid bilayer membranes to serve as model systems for studies of various biological processes including permeability of the plasma membrane and molecular mechanisms of anesthesia. Because the hydrophobic portion of an alcohol favorably interacts with lipid hydrocarbon chains, the polar hydroxyl group remains free to form hydrogen bonds with polar lipid atoms that are located near the water/lipid interface. Experiments on phospholipid membranes have shown that alcohols can induce an interdigitated phase and at high concentration even promote the assembly of some lipids into non-bilayer structures within the membrane interior. In this paper we have investigated the DPPC:hexanol system at high alcohol concentration (two molecules per phospholipid) by means of calorimetric, Nuclear Magnetic Resonance, X-ray diffraction and density measurements. We have found that the presence of a high alcohol concentration shifts the membrane transition temperature to lower values, and has a disordering effect on the phospholipid acyl chains in the gel phase. The bilayer spacing and the area of polar head have been also derived for the liquid phase.

U. Wanderlingh

G. D'Angelo

V. Conti Nibali

C. Crupi

S. Rifici

C. Corsaro

G. Sabatino

Interaction of alcohol with phospholipid membrane: NMR and XRD investigations on DPPC&#x2013;hexanol system

The solution structure and refolding of the Mycobacterium tuberculosis pentapeptide repeat protein MfpA was explored by fluorescence and circular dichroism spectroscopy. Our results show that MfpA exists in two stable structural forms which exclusively favor dimer or oligomer formation. The structural malleability of MfpA may provide a novel target for drug discovery.

S. Khrapunov

H. Cheng

S. Hegde

J. Blanchard

M. Brenowitz

Unusual structural characteristics of the Mycobacterium tuberculosis pentapeptide repeat protein MfpA

Soil-borne fungi are considered as major pathogens to many plants and can cause a severe economic damage. Early detection and identification of these pathogens is very important and might be critical for their control. The available methods for identification of fungi like molecular biology, serological tests and PCRs tests (polymerase chain reaction) are time consuming and not always very specific. Fourier-transform infrared (FTIR) attenuated total reflection (ATR) spectroscopy, is considered to be a comprehensive and sensitive method for detection of molecular changes in intact cells.In the present study we used FTIR–ATR as a sensitive and effective assay for the detection and discrimination between different fungal genera. Our results showed significant spectral differences between the various examined fungi genera. These results proved the possibility of discrimination between these fungi on the genus level.

A. Salman

L. Tsror

A. Pomerantz

R. Moreh

S. Mordechai

M. Huleihel

FTIR spectroscopy for detection and identification of fungal phytopathogenes

The stability of the representatives of two protein classes with &#x3B2;-barrel topology: porcine odorant-binding protein (OBP) and a number of fluorescent proteins (FPs), was studied. It was shown that both of them are significantly more stable than globular α-helical and &#x3B1;&#x2F;&#x3B2; proteins. At the same time the value of energy barrier between native and unfolded state for FPs exceeds that for OBP. It was found that the small guanidine hydrochloride concentrations induce local structural disturbances in proteins: changes in microenvironment of tryptophan residue in the case of odorant-binding protein and decrease in chromophore non-planarity in the case of green fluorescent protein.

Olesya V. Stepanenko

Irina M. Kuznetsova

Vladislav V. Verkhusha

Maria Staiano

Sabato D'Auria

Konstantin K. Turoverov

Denaturation of proteins with beta-barrel topology induced by guanidine hydrochloride

We describe the synthesis of porous spherical nanoaggregates derived by the controlled growth of zeolite LTA on a poliamidoamine (Pamam) dendrimer acting as nano-template. The presence of a strong condensed cationic Na&#x2b; charge all around the dendrimers, which is responsible for the intense electrostatic inter-particle interaction potential, stimulate the condensed growth of the zeolitic phase onto the dendrimer substrate. Moreover, the screening produced by the zeolite grown on the dendrimer surface promote the entanglement process between the primary units with the formation of large porous clusters. The main features of the self-assembly process has been characterised by means of different techniques such as Small Angle X-ray Scattering (SAXS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray (EDX) microprobe spectroscopy. The finding of our results may open new perspectives in the synthesis of organic&#8211;inorganic nanostructured materials based on mesoporous frameworks with new characteristics and properties.

L. Bonaccorsi

D. Lombardo

A. Longo

E. Proverbio

P. Calandra

Pourous nanoparticles formation using a dendrimer template

The HMGB1 protein (High Mobility Group protein 1) participates in the formation of functionally significant DNA-protein complexes. HMGB1 protein contains two DNA-binding domains and negatively charged C-terminal region. The latter consists of continuous sequence of dicarboxylic amino acids residues. Structural changes in DNA-protein complexes were studied by circular dichroism spectroscopy (CD) and atomic force microscopy (AFM). Natural HMGB1 and recombinant protein HMGB1(A + B) lacked negatively charged C-terminal region were used. The DNA–HMGB1(A + B) complexes demonstrate an unusually high optical activity in 150 mM NaCl solutions. AFM of the latter complexes shows, that at the low concentration of HMGB1 in the complex the protein is distributed along DNA in a random way. Increase of HMGB1 content leads to cooperative interaction and a redistribution of the bound protein molecules on DNA is observed. Based on the data obtained we conclude that protein–protein interactions play a key role in the formation of highly ordered DNA–HMGB1 complexes. It was shown that C-terminal domain modulate the interactions of DNA with HMGB1 protein. We suggest that the C-terminal domain of HMGB1 also modulates the “packing” of HMGB1 molecules on the DNA.

E. Chikhirzhina

A. Polyanichko

Z. Leonenko

H. Wieser

V. Vorob'ev

C-terminal domain of nonhistone protein HMGB1 as a modulator of HMGB1–DNA structural interactions

This study is a part of the project focused on the vibrational analysis of natural mono- and polyacetylenes by using Raman spectroscopy and theoretical calculations. Their vibrational spectra show strong and polarized &#8211;C&#8801;C&#8211; bands in the region of about 2200 cm&#8211;1. Mono- as well as polyacetylenes are supposed to be active in plants yet not available in an isolated form, so theoretical simulation of their vibrational spectra and comparison with the registered ones seems to be an excellent way to confirm or exclude the presence of these compounds in the investigated plants. Such an approach was applied here to analyze polyacetylenes in roots of Coreopsis grandiflora. According to literature, this plant should contain a monoacetylene substituted by a thiophene ring. Theoretical calculations allowed to confirm this assumption.

Maciej Roman

Malgorzata Baranska

Natural monoacetylenes studied by quantum-chemical chemistry

The progress of molecular manipulation technology has made it possible to conduct controlled experiments on translocation of polynucleotide and polypeptide chains across alpha-Hemolysin channels and solid-state nanopores. To study the translocation process we combined Molecular Dynamics at coarse-grained level and appropriate drift-diffusion Smoluchowski equations as an integrated statistical physics approach. In particular, we performed simulations of the passage across a cylindrical nanopore of Ubiquitin described by a coarse-grained native-centric model to investigate the influence of protein structural properties on translocation mechanism. The kinetic characterization of the process is achieved by studying the statistics of blockage times, the mobility and translocation probability as a function of the pulling force F acting in the pore. We find that the transport dynamics displays a threshold Fc depending on a free-energy barrier that Ubiquitin overcomes to translocate. Our simulations show this barrier to be the result from competition of the unfolding energy and the entropy associated to the confinement effects of the pore.

Fabio Cecconi

Umberto Marini Bettolo Marconi

Angelo Vulpiani

Translocation process of structured polypeptides across nanopores

The cyclobutane pyrimidine dimer (CPD) formed between two adjacent thymine bases is the most abundant DNA photolesion induced by UV radiation. The quantum yield of this reaction is on the order of ~1% in DNA. This small quantum yield hampers the study of damage formation in naturally occurring DNA. Investigations with increased accuracy become possible for a locked nucleotide model compound TLpTL which exhibits a quantum yield of about 10% for CPD formation. Time resolved IR spectroscopy on TLpTL and two other DNA model compounds (TpT and (dT)18) reveals that: (i) The absorption changes after ~1 ps are due to CPD photodamage. (ii) The quantum efficiency of CPD formation on the few picosecond time scale equals the quantum efficiency reported in stationary experiments. CPD photodamage formation in the investigated DNA constructs is thus predominantly formed from the primarily photoexcited singlet ππ* state, whereas the triplet channel does not play an essential role.

W. J. Schreier

J. Kubon

P. Clivio

W. Zinth

P. Gilch

DNA photodamage: Study of cyclobutane pyrimidine dimer formation in a locked thymine dinucleotide

A green Chlorophycean micro-alga surviving high irradiation doses has been discovered in the storage pools of a nuclear reactor. Investigating the mechanisms sustaining its properties is of peculiar interest. Metabolic impact of irradiation on the micro-alga as well as structural macromolecular impact were investigated using nuclear magnetic resonance and neutron backscattering spectroscopy. Carbohydrate, amino acid and organic acid content studied as a function of the irradiation dose revealed an intense protein repair activity. Resilience was extracted according to irradiation dose and compared to that of other extremophile species.

Corinne Rivasseau

Emmanuel Farhi

Marina Gromova

Jacques Ollivier

Richard Bligny

Resistance to irradiation of micro-algae growing in the storage pools of a nuclear reactor investigated by NMR and neutron spectroscopies

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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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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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