http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Mon, 15 Apr 2013 10:48:59 +0000 http://www.hindawi.com/isrn/biophysics/2013/740821/ Food-borne heterocyclic aromatic amines (HCAs) are known mutagens and carcinogens present especially in Western population diet, which contains large amount of meat and its products. HCAs are capable of interacting with DNA directly through the formation of covalent adducts, however this process requires biological activation in liver, mainly by cytochrome P450 enzymes. This process may produce mutations and in consequence may contribute to the development of cancer. However, there are many studies showing that several biologically active aromatic compounds (BACs) may protect against genotoxic effects of HCAs. Direct interactions and noncovalent heterocomplexes formation may be one of the most important mechanisms of such protection. This work describes several BACs present in human diet, which are capable of molecular complexes formation with HCAs and protect cells as well as whole organisms against HCAs action. Anna Woziwodzka, Grzegorz Gołuński, and Jacek Piosik Copyright © 2013 Anna Woziwodzka et al. All rights reserved. Sun, 14 Apr 2013 09:34:08 +0000 http://www.hindawi.com/isrn/biophysics/2013/948074/ Previously it has been shown that cell hydration is a universal and extrasensitive marker for different environmental mediums and functional state of tissue and organism. The comparative study of cell hydration of different organs (brain cortex, liver, and skeletal muscle) at various experimental conditions (microstress, pathology, and different poisons) was realized. It was shown that among tissues of different organs muscle hydration is more sensitive to any change of functional state of organism and environmental medium. The study of correlation between tissue muscle hydration and double-frequency measurement impedance method indicated that the differences between muscle reactive conductivity measured at high frequency (HF) and low frequency (LF) could be an adequate marker for detection of muscle hydration. The animal poisoning, stress, and pathology-induced tissue hydration were accompanied by increase in . The observed close correlation between time-dependent tissue hydration and in different environmental mediums can be a marker for detection of postmortal period as well as for characterizing environmental medium of the corpse. Anush Deghoyan, Robert Simonyan, Howard Wachtel, and Sinerik Ayrapetyan Copyright © 2013 Anush Deghoyan et al. All rights reserved. Sun, 31 Mar 2013 10:00:03 +0000 http://www.hindawi.com/isrn/biophysics/2013/439758/ Diffusion is the fundamental mechanism for lipids and other molecules to move in a membrane. It is an important process to consider in modelling the formation of membrane structures, such as rafts. Lipid diffusion is mainly studied by two different techniques: incoherent neutron scattering and fluorescence microscopy. Both techniques access distinctly different length scales. While neutron scattering measures diffusion over about 3 lipid diameters, microscopic techniques access motions of lipids over micrometer distances. The diffusion constants which are determined by these two methods often differ by about an order of magnitude, with the neutrons usually seeing a faster lipid diffusion. Different theories are used to describe lipid diffusion in the two experiments. In order to close the “gap” between these two techniques, we propose to study lipid diffusion at mesoscopic length scales using a neutron spin-echo (NSE) spectrometer. We have conducted an experiment in highly oriented, solid supported lipid bilayers to prove the feasibility of performing incoherent NSE on biological samples. Lateral lipid diffusion was measured in a fluid phase model membrane system at a length scale of 12 Å. Using the high-energy resolution of the NSE technique, we find evidence for two dynamic processes. Clare L. Armstrong, Laura Toppozini, Hannah Dies, Antonio Faraone, Michihiro Nagao, and Maikel C. Rheinstädter Copyright © 2013 Clare L. Armstrong et al. All rights reserved. Wed, 05 Dec 2012 14:07:52 +0000 http://www.hindawi.com/isrn/biophysics/2012/972085/ The effect of Anderson localization in DNA on the Auger destruction by the Coulombic explosion at ionized radiation has been theoretically discussed in the present work. The theory of Auger destruction of DNA has been modified taking into account the localized and delocalized electron states in DNA owing to the correlated disorder in a sequence of nucleotides. According to the modified theoretical model of Auger destruction, the dominant ratio of delocalized states to localized states in exon compared to intron results in stronger radiation resistance of exons to ionized irradiation causing the Auger-cascade process than the radiation resistance of introns. N. N. Turaeva, S. Schroeder, and B. L. Oksengendler Copyright © 2012 N. N. Turaeva et al. All rights reserved. Sun, 09 Sep 2012 16:18:48 +0000 http://www.hindawi.com/isrn/biophysics/2012/947872/ Many insects have evolved refined self-cleaning membrane structuring to contend with an environment that presents a range of potential contaminates. Contamination has the potential to reduce or interfere with the primary functioning of the wing membrane or affect other wing cuticle properties, (for example, antireflection). Insects will typically encounter a variety of air-borne contaminants which include plant matter and soil fragments. Insects with relatively long or large wings may be especially susceptible to fouling due to the high-wing surface area and reduced ability to clean their extremities. In this study we have investigated the adhesion of particles (pollens and hydrophilic silica spheres) to wing membranes of the super/hydrophobic cicada (Thopha sessiliba), butterfly (Eurema hecabe), and the hydrophilic wing of flower wasp (Scolia soror). The adhesional forces with both hydrophobic insects was significantly lower for all particle types than the hydrophilic insect species studied. Gregory S. Watson, Bronwen W. Cribb, and Jolanta A. Watson Copyright © 2012 Gregory S. Watson et al. All rights reserved. Wed, 13 Jun 2012 14:33:33 +0000 http://www.hindawi.com/isrn/biophysics/2012/839040/ Magnetoreception is a sophisticated orientation mechanism, involving a magnetoreceptor connected to the nervous system with signal amplification. The mollusk Tritonia diomedea is a good model to investigate the behavioral and neural responses to the magnetic field. The mollusk inhibits all unnecessary activities and focuses on an available cue during orientation. Although Pd7 cells are inhibited by magnetic pathway, it was excited by another stimulus, water streams plus food odor. Two sensory pathways connected to Pd7 through the same or different circuits were tested. The action potential activity through Pd7 was compared in these different stimulations. The changes in Pd7 activity indicate a response of enhanced electrical activity to water streams plus food odor stimulus, and Pd7 activity can be excited by at least one of these stimuli. These results indicate an inverse relationship between magnetic orientation and feeding. L. G. Abraçado Copyright © 2012 L. G. Abraçado. All rights reserved. Tue, 05 Jun 2012 10:44:53 +0000 http://www.hindawi.com/isrn/biophysics/2012/520307/ We present a high-temperature and high-energy resolution neutron scattering investigation of hydration water freezing in single supported lipid bilayers. Single supported lipid bilayers provide a well-defined biological interface to study hydration water dynamics and coupling to membrane degrees of freedom. Nanosecond molecular motions of membrane and hydration water were studied in the temperature range 240 K < T < 290 K in slow heating and cooling cycles using coherent and incoherent elastic neutron scattering on a backscattering spectrometer. Several freezing and melting transitions were observed. From the length scale dependence of the elastic scattering, these transitions could be assigned to freezing and melting of hydration water dynamics, diffusive lipid, and lipid acyl-tail dynamics. Coupling was investigated by comparing the different freezing and melting temperatures. While it is often speculated that membrane and hydration water dynamics are strongly coupled, we find that membrane and hydration water dynamics are at least partially decoupled in single bilayers. Laura Toppozini, Clare L. Armstrong, Martin D. Kaye, Madhusudan Tyagi, Timothy Jenkins, and Maikel C. Rheinstädter Copyright © 2012 Laura Toppozini et al. All rights reserved. Sun, 22 Apr 2012 14:19:23 +0000 http://www.hindawi.com/isrn/biophysics/2012/906761/ The aim of current paper was to investigate the possibility of increasing the toxicity of calcium hypochlorite (Ca(ClO)2) and hydrogen peroxide (H2O2) on Escherichia coli K-12 by preliminary enrichment of culture media by carbon dioxide (CO2). For this purpose, the microbes sensitivity to H2O2 or/and Ca(ClO)2 at normal and CO2-enriched medium was studied by spectrophotometric, radioisotopic, and electronmicroscopic methods. Ten-minute preincubation in CO2-enriched medium enhanced the toxic effect of both H2O2 or/and Ca(ClO)2 on bacteria as a result of induced growth inhibition, compared to no-CO2 enriched group. Additionally, changes in cell morphology and proliferation were observed. It was demonstrated that the preliminary incubation of microbes in CO2-enriched culture media in nonsupercritical concentration elevate the toxic effect of H2O2 or/and Ca(ClO)2 on microbes. This can serve as a novel, effective, inexpensive, and environmentally friendly approach for water purification from bacteria, further improving the protection of the environment and human health. Varsik Martirosyan, Karlen Hovnanyan, and Sinerik Ayrapetyan Copyright © 2012 Varsik Martirosyan et al. All rights reserved. Sun, 25 Mar 2012 15:51:49 +0000 http://www.hindawi.com/isrn/biophysics/2012/937265/ The direct electrochemistry of cytochrome c (cyt c) immobilized on a modified carbon paste electrode (CPE) was described. The electrode was modified with ZnO nanoparticles. Direct electrochemistry of cytochrome c in this paste electrode was easily achieved, and a pair of well-defined quasireversible redox peaks of a heme Fe (III)/Fe(II) couple appeared with a formal potential (E0) of −0.303 V (versus SCE) in pH 7.0 phosphate buffer solution (PBS). The fabricated modified bioelectrode showed good electrocatalytic ability for reduction of H2O2. The preparation process of the proposed biosensor was convenient, and the resulting biosensor showed high sensitivity, low detection limit, and good stability. Masoud Negahdary, Saeed Rezaei-Zarchi, Neda Rousta, and Soheila Samei Pour Copyright © 2012 Masoud Negahdary et al. All rights reserved. Wed, 14 Mar 2012 11:05:11 +0000 http://www.hindawi.com/isrn/biophysics/2012/124803/ The absolute values of the metal-binding energies of human serum transferrin (Tf) N-lobe, |ΔE|, were calculated using the density functional theory and were found to increase in magnitude in the following order: Fe(III)>Ga(III)>Al(III)>Cu(II)>Zn(II)>Ni(II). The calculated energies were well correlated with the logarithmic values of the reported metal-binding constants of Tf, which had been experimentally determined, with a correlation coefficient of 0.96. In the estimation of the binding energies, the solvation energies (solvent effect) of free metal ions were a very important factor. The results provide a theoretical explanation for the binding of Fe(III) to Tf, which produces sufficient energy to induce a conformational transition of the Tf molecule, making it possible to interact with Tf receptor 1. Tetsuya Sakajiri, Hirofumi Yajima, and Takaki Yamamura Copyright © 2012 Tetsuya Sakajiri et al. All rights reserved. Tue, 07 Feb 2012 12:02:18 +0000 http://www.hindawi.com/isrn/biophysics/2012/786596/ Oncogenes are rich in guanine and capable of forming quadruplex structure. Promoter regions oncogenes such as Bcl2 and KRAS NHPPE are rich in guanine content and they can form quadruplex structures. Alterations in the mode and nature of molecular binding to DNA, certainly has effect on the posttranscriptional activities. Recent experiments indicate that structure of quadruplex complex and ligand has predominant role on ligand-quadruplex DNA interaction. In order to understand the nature of each ligand interaction with quadruplex DNA, Bcl2, KRAS NHPPE quadruplex DNA interaction with three porphyrin was studied using spectroscopy, microcalorimetry and mass spectrometry. Our studies, indicate that mode of ligand interaction varies with structure, environment and concentration of ligand. Fluorescence quenching experiments show that TMPyP4 interaction is ligand concentration dependent. Job plots and ITC experiments demonstrate that four molecules of TMPyP4 and two molecules of TMPyP3, TMPyP2 interact with each quadruplex complex. Through ITC titrations, ligand binding constant are higher for TMPyP4 (≈107 M−1) compared to TMPyP3, TMPyP2 (≈105 M−1). ESI-MS experiments confirm the stoichiometry of TMPyP4 : 39Bcl2 is 4 : 1 at saturation and it is 2 : 1 in case of KRAS NHPPE quadruplex. Narayana Nagesh and Arumugam Ganesh Kumar Copyright © 2012 Narayana Nagesh and Arumugam Ganesh Kumar. All rights reserved. Thu, 15 Dec 2011 10:59:35 +0000 http://www.hindawi.com/isrn/biophysics/2012/725350/ Breaks in DNA, resulting in fragmented parts, can be produced by ionizing radiation which, in turn, is the starting point in the search for novel physical aspects of DNA strands. Double-strand breaks in particular cause disruption of the DNA strand, splitting it into several fragments. In order to study effects produced by radiation in plasmid DNA, a new simple mechanical model for this molecule is proposed. In this model, a Morse-like potential and a high-LET component are used to describe the DNA-radiation interaction. Two power laws, used to fit results of the model, suggest that, firstly, distribution of fragment size is nonextensive and, secondly, that a transition phase is present in the DNA fragment distribution pattern. R. A. S. Silva, J. D. T. Arruda-Neto, and L. Nieto Copyright © 2012 R. A. S. Silva et al. All rights reserved.