Social and Behavioral Sciences Commons^™

Activity And Molecular Dynamics Relationship Within The Family Of Human Cholinesterase, Judith Peters, Marie Trovaslet, Marcus Trapp, Florian Nachon, Flynn Hill, Etienne Royer, Frank Gabel, Lambert Van Eijck, Patrick Masson, Moeava Tehei

Faculty of Science - Papers (Archive)

The temperature dependence of the dynamics of recombinant human acetylcholinesterase (hAChE) and plasma human butyrylcholinesterase (hBChE) is examined using elastic incoherent neutron scattering. These two enzymes belong to the same family and present 50% amino acid sequence identity. However, significantly higher flexibility and catalytic activity of hAChE when compared to the ones of hBChE are measured. At the same time, the average height of the potential barrier to the motions is increased in the hBChE, e.g. more thermal energy is needed to cross it in the latter case, which might be the origin of the increase in activation energy and …

Molecular Dynamics Analysis Of Apolipoprotein-D - Lipid Hydroperoxide Interactions: Mechanism For Selective Oxidation Of Met-93, Aaron J. Oakley, Surabhi Bhatia, Heath Ecroyd, Brett Garner

Faculty of Science - Papers (Archive)

Background: Recent studies suggest reduction of radical-propagating fatty acid hydroperoxides to inert hydroxides by interaction with apolipoprotein-D (apoD) Met93 may represent an antioxidant function for apoD. The nature and structural consequences of this selective interaction are unknown.

Methodology/Principal Findings: Herein we used molecular dynamics (MD) analysis to address these issues. Longtimescale simulations of apoD suggest lipid molecules are bound flexibly, with the molecules free to explore multiple conformations in a binding site at the entrance to the classical lipocalin ligand-binding pocket. Models of 5s- 12s- and 15s hydroperoxyeicosatetraenoic acids were created and the lipids found to wrap around Met93 thus …

Telomere Dynamics And Homeostasis In A Transmissible Cancer, Beata Ujvari, Anne-Maree Pearse, Robyn Taylor, Stephen Pyecroft, Cassandra Flanagan, Sara Gombert, Anthony T. Papenfuss, Thomas R. Madsen, Katherine Belov

Faculty of Science - Papers (Archive)

Background: Devil Facial Tumour Disease (DFTD) is a unique clonal cancer that threatens the world's largest carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii) with extinction. This transmissible cancer is passed between individual devils by cell implantation during social interactions. The tumour arose in a Schwann cell of a single devil over 15 years ago and since then has expanded clonally, without showing signs of replicative senescence; in stark contrast to a somatic cell that displays a finite capacity for replication, known as the "Hayflick limit". Methodology/Principal Findings: In the present study we investigate the role of telomere length, measured as …

From Ecophysiology To Phenomics: Some Implications Of Photoprotection And Shade-Sun Acclimation In Situ For Dynamics Of Thylakoids In Vitro, Shizue Matsubara, Britta Forster, Melinda Waterman, Sharon A. Robinson, Barry J. Pogson, Brian Gunning, Barry Osmond

Faculty of Science - Papers (Archive)

Half a century of research into the physiology and biochemistry of sun–shade acclimation in diverse plants has provided reality checks for contemporary understanding of thylakoid membrane dynamics. This paper reviews recent insights into photosynthetic efficiency and photoprotection from studies of two xanthophyll cycles in old shade leaves from the inner canopy of the tropical trees Inga sapindoides and Persea americana (avocado). It then presents new physiological data from avocado on the time frames of the slow coordinated photosynthetic development of sink leaves in sunlight and on the slow renovation of photosynthetic properties in old leaves during sun to shade and …

Book Review - Women In Leadership: Contextual Dynamics And Boundaries, Christine Eriksen

Faculty of Science - Papers (Archive)

Leadership scenarios and paradoxes - past, present and future - form the basis of Karin Klenke's analysis of women in leadership. The book sets out to explore the paradoxical nature of women's leadership in male-dominated contexts, paradoxes women leaders are confronted with, as well as the paradox of change versus the persistence of the status quo. Contexts with a 'paradoxical nature'- temporally and spatially - are at the forefront. These 'contexts' for women's leadership range from remarkable female leaders, today and historically, in politics, organisational structures, information technology (IT), the media, sports, the military, religion and spirituality, science, higher education …

Elastic Scattering Studies Of Aligned Dmpc Multilayers On Different Hydrations, Marcus Trapp, Fanni Juranyi, Moeava Tehei, Lambert Van Eijck, Bruno Demé, Thomas Gutberlet, Judith Peters

Faculty of Science - Papers (Archive)

Biological membranes, consisting mainly of phospholipids and proteins, are organized in a bilayered structure which exhibits dynamical behaviour within time regimes ranging from 10-12 s with the motion of alkyl chain defects and 1 s corresponding to collective excitations of the bilayer [1]. With the prominent role hydration plays on the structural phase behaviour of phospholipids membranes, it is essential for a better description of membranes to understand also the influence of hydration on the dynamics of membrane systems. In the present study we have performed neutron scattering investigations on highly oriented DMPC-d54 multilayers at two different relative humidity (rh) …

Specific Cellular Water Dynamics Observed In Vivo By Neutron Scattering And Nmr., Moeava Tehei, Marion Jasnin, Andreas Stadler, Giuseppe Zaccai

Faculty of Science - Papers (Archive)

Neutron scattering, by using deuterium labelling, revealed how intracellular water dynamics, measured in vivo in E. coli, human red blood cells and the extreme halophile, Haloarcula marismortui, depends on the cell type and nature of the cytoplasm. The method uniquely permits the determination of motions on the molecular length (Ba˚ ngstrøm) and time (pico- to nanosecond) scales. In the bacterial and human cells, intracellular water beyond the hydration shells of cytoplasmic macromolecules and membrane faces flows as freely as liquid water. It is not ‘‘tamed’’ by confinement. In contrast, in the extreme halophile archaeon, in addition to free and hydration …

Short Telomeres In Hatchling Snakes: Erythrocyte Telomere Dynamics And Longevity In Tropical Pythons, Beata Ujvari, Thomas Madsen

Faculty of Science - Papers (Archive)

Background: Telomere length (TL) has been found to be associated with life span in birds and humans. However, other studies have demonstrated that TL does not affect survival among old humans. Furthermore, replicative senescence has been shown to be induced by changes in the protected status of the telomeres rather than the loss of TL. In the present study we explore whether age- and sex-specific telomere dynamics affect life span in a long-lived snake, the water python (Liasis fuscus). Methodology/Principal Findings: Erythrocyte TL was measured using the Telo TAGGG TL Assay Kit (Roche). In contrast to other vertebrates, TL of …

Base-Induced Decomposition Of Alkyl Hydroperoxides In The Gas Phase. Part 3. Kinetics And Dynamics In Ho + Ch3ooh, C2h5ooh, And Tert-C4h9ooh Reactions, Shuji Kato, G Barney Ellison, Veronica Bierbaum, Stephen J. Blanksby

Faculty of Science - Papers (Archive)

The E_CO2 elimination reactions of alkyl hydroperoxides proceed via abstraction of an α-hydrogen by a base: X⁻ + R¹R²HCOOH → HX + R¹R²CO + HO⁻. Efficiencies and product distributions for the reactions of the hydroxide anion with methyl, ethyl, and tert-butyl hydroperoxides are studied in the gas phase. On the basis of experiments using three isotopic analogues, HO⁻ + CH₃OOH, HO⁻ + CD₃OOH, and H¹⁸O⁻ + CH₃OOH, the overall intrinsic reaction efficiency is determined to …

Anisotropic Atomic Motions In High-Resolution Protein Crystallography Molecular Dynamics Simulations, Conrad J. Burden, Aaron J. Oakley

Faculty of Science - Papers (Archive)

Molecular dynamics (MD) simulations using empirical force fields are popular for the study of proteins. In this work, we compare anisotropic atomic fluctuations in nanosecond-timescale MD simulations with those observed in an ultra-high-resolution crystal structure of crambin. In order to make our comparisons, we have developed a compact graphical technique for assessing agreement between spatial atomic distributions determined by MD simulations and observed anisotropic temperature factors.

Fundamental And Biotechnological Applications Of Neutron Scattering Measurements For Macromolecular Dynamics, M. Tehei, R. Daniel, G. Zaccai

Faculty of Science - Papers (Archive)

To explore macromolecular dynamics on the picosecond timescale, we used neutron spectroscopy. First, molecular dynamics were analyzed for the hyperthermophile malate dehydrogenase from Methanococcus jannaschii and a mesophilic homologue, the lactate dehydrogenase from Oryctolagus cunniculus muscle. Hyperthermophiles have elaborate molecular mechanisms of adaptation to extremely high temperature. Using a novel elastic neutron scattering approach that provides independent measurements of the global flexibility and of the structural resilience (rigidity), we have demonstrated that macromolecular dynamics represents one of these molecular mechanisms of thermoadaptation. The flexibilities were found to be similar for both enzymes at their optimal activity temperature and the resilience …

Dynamics Of Immobilized And Native Escherichia Coli Dihydrofolate Reductase By Quasielastic Neutron Scattering, M. Tehei, J. Smith, C. Monk, J. Ollivier, M. Oettl, V. Kurkal, J. L. Finney, R. M. Daniel

Faculty of Science - Papers (Archive)

The internal dynamics of native and immobilized Escherichia coli dihydrofolate reductase (DHFR) have been examined using incoherent quasielastic neutron scattering. These results reveal no difference between the high frequency vibration mean-square displacement of the native and the immobilized E. coli DHFR. However, length-scale-dependent, picosecond dynamical changes are found. On longer length scales, the dynamics are comparable for both DHFR samples. On shorter length scales, the dynamics is dominated by local jump motions over potential barriers. The residence time for the protons to stay in a potential well is t=7.95 ps for the native DHFR and t=20.36 ps for the immobilized …

Structure And Dynamics Of Sponge-Dominated Assemblages On Exposed And Sheltered Temperate Reefs, D. E. Roberts, S. P. Cummins, A. R. Davis, M. G. Chapman

Faculty of Science - Papers (Archive)

There have been few studies on the structure and dynamics of sponge-dominated assemblages, despite the fact that such assemblages are vulnerable to environmental impacts from many anthropogenic disturbances. Sponges are generally slow to recruit, slow growing and long lived; hence, they may be very vulnerable to anthropogenic and natural disturbances. In order to understand how such assemblages may respond to disturbance, it is essential to measure natural patterns of spatial differences and temporal changes, so that any future impact assessments can be identified. This study quantified and contrasted patterns of abundance in sponge-dominated assemblages on deep reefs (18 to 20 …

Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We have performed molecular dynamics (MD) simulations to study the dimerization, folding, and binding to a protein of peptides containing an unnatural amino acid. NMR studies have shown that the substitution of one residue in a tripeptide β-strand by the unnatural amino acid Hao (5-HO2CCONH-2-MeO-C6H3-CO-NHNH2) modifies the conformational flexibility of the β-strand and the hydrogen-bonding properties of its two edges: The number of hydrogen-bond donors and acceptors increases at one edge, whereas at the other, they are sterically hindered. In simulations in chloroform, the Hao-containing peptide 9 (i-PrCO-Phe-Hao-Val-NHBu) forms a β-sheet–like hydrogen-bonded dimer, in good agreement with the available experimental …

Molecular Dynamics Simulation Of Biomolecular Systems, Wilfred Van Gunsteren, Dirk Bakowies, Roland Buergi, Indira Chandrasekhar, Markus Christen, Xavier Daura, Peter Gee, Alice Glaettli, Tomas Hansson, Chris Oostenbrink, Christine Peter, Jed Pitera, Lukas Schuler, Thereza Soares, Haibo Yu

Faculty of Science - Papers (Archive)

The group for computer-aided chemistry at the ETH Zurich focuses its research on the development of methodology to simulate the behavior of biomolecular systems and the use of simulation techniques to analyze and understand biomolecular processes at the atomic level. Here, the current research directions are briefly reviewed and illustrated with a few examples.