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Wennberg CL, Murtola T, Hess B, Lindahl E. Lennard-Jones Lattice Summation in Bilayer Simulations Has Critical Effects on Surface Tension and Lipid Properties. J Chem Theory Comput 2013; 9:3527-37. [DOI: 10.1021/ct400140n] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Pronk S, Páll S, Schulz R, Larsson P, Bjelkmar P, Apostolov R, Shirts MR, Smith JC, Kasson PM, van der Spoel D, Hess B, Lindahl E. GROMACS 4.5: a high-throughput and highly parallel open source molecular simulation toolkit. Bioinformatics 2013; 29:845-54. [PMID: 23407358 PMCID: PMC3605599 DOI: 10.1093/bioinformatics/btt055] [Citation(s) in RCA: 4996] [Impact Index Per Article: 454.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/28/2013] [Accepted: 01/29/2013] [Indexed: 01/27/2023] Open
Abstract
MOTIVATION Molecular simulation has historically been a low-throughput technique, but faster computers and increasing amounts of genomic and structural data are changing this by enabling large-scale automated simulation of, for instance, many conformers or mutants of biomolecules with or without a range of ligands. At the same time, advances in performance and scaling now make it possible to model complex biomolecular interaction and function in a manner directly testable by experiment. These applications share a need for fast and efficient software that can be deployed on massive scale in clusters, web servers, distributed computing or cloud resources. RESULTS Here, we present a range of new simulation algorithms and features developed during the past 4 years, leading up to the GROMACS 4.5 software package. The software now automatically handles wide classes of biomolecules, such as proteins, nucleic acids and lipids, and comes with all commonly used force fields for these molecules built-in. GROMACS supports several implicit solvent models, as well as new free-energy algorithms, and the software now uses multithreading for efficient parallelization even on low-end systems, including windows-based workstations. Together with hand-tuned assembly kernels and state-of-the-art parallelization, this provides extremely high performance and cost efficiency for high-throughput as well as massively parallel simulations. AVAILABILITY GROMACS is an open source and free software available from http://www.gromacs.org. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Mikhailov AS, Hess B. Self-organization in living cells: networks of protein machines and nonequilibrium soft matter. J Biol Phys 2013; 28:655-72. [PMID: 23345805 DOI: 10.1023/a:1021247024192] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Microscopic self-organization phenomena inside a living cell should not represent merely a reduced copy of self-organization in macroscopic systems. A cell is populated by active protein machines that communicate via small molecules diffusing through the cytoplasm. Mutual synchronization of machine cycles can spontaneously develop in such networks - an effect which is similar to coherent laser generation. On the other hand, an interplay between reactions, diffusion and phase transitions in biological soft matter may lead to the formation of stationary or traveling nonequilibrium nanoscale structures.
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Kasson PM, Hess B, Lindahl E. Probing microscopic material properties inside simulated membranes through spatially resolved three-dimensional local pressure fields and surface tensions. Chem Phys Lipids 2013; 169:106-12. [PMID: 23318532 DOI: 10.1016/j.chemphyslip.2013.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 12/19/2012] [Accepted: 01/02/2013] [Indexed: 11/24/2022]
Abstract
Cellular lipid membranes are spatially inhomogeneous soft materials. Materials properties such as pressure and surface tension thus show important microscopic-scale variation that is critical to many biological functions. We present a means to calculate pressure and surface tension in a 3D-resolved manner within molecular-dynamics simulations and show how such measurements can yield important insight. We also present the first corrections to local virial and pressure fields to account for the constraints typically used in lipid simulations that otherwise cause problems in highly oriented systems such as bilayers. Based on simulations of an asymmetric bacterial ion channel in a POPC bilayer, we demonstrate how 3D-resolved pressure can probe for both short-range and long-range effects from the protein on the membrane environment. We also show how surface tension is a sensitive metric for inter-leaflet equilibrium and can be used to detect even subtle imbalances between bilayer leaflets in a membrane-protein simulation. Since surface tension is known to modulate the function of many proteins, this effect is an important consideration for predictions of ion channel function. We outline a strategy by which our local pressure measurements, which we make available within a version of the GROMACS simulation package, may be used to design optimally equilibrated membrane-protein simulations.
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de Wijn AS, Hess B, Fine BV. Largest Lyapunov exponents for lattices of interacting classical spins. PHYSICAL REVIEW LETTERS 2012; 109:034101. [PMID: 22861854 DOI: 10.1103/physrevlett.109.034101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Indexed: 06/01/2023]
Abstract
We investigate how generic the onset of chaos in interacting many-body classical systems is in the context of lattices of classical spins with nearest-neighbor anisotropic couplings. Seven large lattices in different spatial dimensions were considered. For each lattice, more than 2000 largest Lyapunov exponents for randomly sampled Hamiltonians were numerically computed. Our results strongly suggest the absence of integrable nearest-neighbor Hamiltonians for the infinite lattices except for the trivial Ising case. In the vicinity of the Ising case, the largest Lyapunov exponents exhibit a power-law growth, while further away they become rather weakly sensitive to the Hamiltonian anisotropy. We also provide an analytical derivation of these results.
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Schwaiger CS, Börjesson SI, Hess B, Elinder F, Lindahl E. Phe233 in the Voltage-Sensor is Rate Limiting for Channel Closure but not for the Opening. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Brown CJ, Sinclair RA, Day A, Hess B, Procter P. An approximate model for cancellous bone screw fixation. Comput Methods Biomech Biomed Engin 2011; 16:443-50. [PMID: 22149043 DOI: 10.1080/10255842.2011.624516] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.
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Elber R, Ruymgaart AP, Hess B. SHAKE parallelization. THE EUROPEAN PHYSICAL JOURNAL. SPECIAL TOPICS 2011; 200:211-223. [PMID: 22368766 PMCID: PMC3285512 DOI: 10.1140/epjst/e2011-01525-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
SHAKE is a widely used algorithm to impose general holonomic constraints during molecular simulations. By imposing constraints on stiff degrees of freedom that require integration with small time steps (without the constraints) we are able to calculate trajectories with time steps larger by approximately a factor of two. The larger time step makes it possible to run longer simulations. Another approach to extend the scope of Molecular Dynamics is parallelization. Parallelization speeds up the calculation of the forces between the atoms and makes it possible to compute longer trajectories with better statistics for thermodynamic and kinetic averages. A combination of SHAKE and parallelism is therefore highly desired. Unfortunately, the most widely used SHAKE algorithm (of bond relaxation) is inappropriate for parallelization and alternatives are needed. The alternatives must minimize communication, lead to good load balancing, and offer significantly better performance than the bond relaxation approach. The algorithm should also scale with the number of processors. We describe the theory behind different implementations of constrained dynamics on parallel systems, and their implementation on common architectures.
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Choi HJ, Lim JS, Park EJ, Jung HJ, Lee YJ, Kwon TH, Cesar KR, Araujo M, de Braganca AC, Magaldi AJ, Freisinger W, Ditting T, Heinlein S, Schatz J, Veelken R, Burki R, Mohebbi N, Wang X, Serra A, Wagner C, Ditting T, Freisinger W, Rodionova K, Heinlein S, Schmieder R, Veelken R, Yano Y, Kudo LH, Magaldi AJ, Choi HJ, Yoon YJ, Lim JS, Hwang GS, Kwon TH, Jo CH, Kim S, Park JS, Lee CH, Kang CM, Kim GH, Kokeny G, Szoleczky P, Fang L, Rosivall L, Mozes MM, Freisinger W, Schatz J, Lampert A, Ditting T, Veelken R, Yano Y, Magaldi AJ, LEE WC, Wang YC, Chen JB, Santos C, Gomes AM, Ventura A, Almeida C, Seabra J, Daher E, Leite de Figueiredo P, Montenegro R, Montenegro R, Martins M, Bezerra da Silva G, Liborio A, Sromicki J, Matter S, Sitzmann K, Hess B, Lee J, Kim S, Lee JW, Oh YK, Na KY, Joo KW, Earm JH, Han JS, Ninchoji T, Kaito H, Nozu K, Hashimura Y, Nakanishi K, Yoshikawa N, Iijima K, Matsuo M, Gorini A, Addesse R, Comegna C, Galderisi C, Cecilia A, Tomaselli M, Di Lullo L, Polito P. Acid-base/Na, K, Cl. Experimental and clinical. Clin Kidney J 2011. [DOI: 10.1093/ndtplus/4.s2.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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van der Spoel D, Hess B. GROMACS—the road ahead. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2011. [DOI: 10.1002/wcms.50] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Ganguly P, Schravendijk P, Hess B, van der Vegt NFA. Ion Pairing in Aqueous Electrolyte Solutions with Biologically Relevant Anions. J Phys Chem B 2011; 115:3734-9. [DOI: 10.1021/jp201150q] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Schwaiger C, Bjelkmar P, Hess B, Lindahl E. 3₁₀-helix conformation facilitates the transition of a voltage sensor S4 segment toward the down state. Biophys J 2011; 100:1446-54. [PMID: 21402026 PMCID: PMC3059565 DOI: 10.1016/j.bpj.2011.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 12/20/2010] [Accepted: 02/02/2011] [Indexed: 10/18/2022] Open
Abstract
The activation of voltage-gated ion channels is controlled by the S4 helix, with arginines every third residue. The x-ray structures are believed to reflect an open-inactivated state, and models propose combinations of translation, rotation, and tilt to reach the resting state. Recently, experiments and simulations have independently observed occurrence of 3(10)-helix in S4. This suggests S4 might make a transition from α- to 3(10)-helix in the gating process. Here, we show 3(10)-helix structure between Q1 and R3 in the S4 segment of a voltage sensor appears to facilitate the early stage of the motion toward a down state. We use multiple microsecond-steered molecular simulations to calculate the work required for translating S4 both as α-helix and transformed to 3(10)-helix. The barrier appears to be caused by salt-bridge reformation simultaneous to R4 passing the F233 hydrophobic lock, and it is almost a factor-two lower with 3(10)-helix. The latter facilitates translation because R2/R3 line up to face E183/E226, which reduces the requirement to rotate S4. This is also reflected in a lower root mean-square deviation distortion of the rest of the voltage sensor. This supports the 3(10) hypothesis, and could explain some of the differences between the open-inactivated- versus activated-states.
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Hess B. [Medical management of acute renal colic - there is more than hydration and Buscopan®...]. PRAXIS 2011; 100:293-297. [PMID: 21365560 DOI: 10.1024/1661-8157/a000450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Renal colic is generated by hyperperistalsis of the obstructed ureter. Peristalsis is modulated by (among others) alpha-receptors (contraction), beta-receptors (relaxation) and prostaglandins (PG F2alpha: contraction, PG E1/E2: relaxation). Non-steroidal anti-inflammatory drugs (NSAID) are highly effective in pain relief and should always be given in the absence of contraindications. The same is true for metamizole, whereas Buscopan® is not superior to placebo. For most severe pain, opioids are indicated. alpha-blockers and calcium channel blockers dilate the distal ureter and increase the likelihood of spontaneous stone passage by up to 65%. Overhydration of patients has no advantage, but carries the risk of pelvic rupture with urine extravasation and infection. Stones of/above diameter 7 mm are unlikely to pass spontaneously and should be interventionally removed.
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Larsson P, Hess B, Lindahl E. Algorithm improvements for molecular dynamics simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2011. [DOI: 10.1002/wcms.3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Engin O, Villa A, Sayar M, Hess B. Driving Forces for Adsorption of Amphiphilic Peptides to the Air−Water Interface. J Phys Chem B 2010; 114:11093-101. [DOI: 10.1021/jp1024922] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Müller SC, Plesser T, Hess B. The structure of the core of the spiral wave in the belousov-zhabotinskii reaction. Science 2010; 230:661-3. [PMID: 17797290 DOI: 10.1126/science.230.4726.661] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The quantitative structure of the core of the spiral-shaped traveling wave of chemical activity appearing in a thin excitable layer of the Belousov-Zhabotinskii reaction, in which the oxidation and decarboxylation of malonic acid by bromate ions is catalyzed by ferroin, was analyzed experimentally. Light absorption by ferroin as the reduced reaction catalyst and indicator was measured by means of a video-and computer-based two-dimensional spectrophotometer with 10-micrometer spatial, 2-second temporal, and 256-digital units intensity resolution. The spiral core is a singular site (diameter, 30 micrometers or less) at which intensity modulations due to ferroin-ferriin distributions are at least ten times smaller than in the surrounding area of spiral propagation. Archimedian spirals were fitted to isoconcentration lines.
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Foerster P, Müller SC, Hess B. Critical size and curvature of wave formation in an excitable chemical medium. Proc Natl Acad Sci U S A 2010; 86:6831-4. [PMID: 16594068 PMCID: PMC297943 DOI: 10.1073/pnas.86.18.6831] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The critical radius for the outward propagation of waves in an excitable solution of the Belousov-Zhabotinskii reaction was experimentally analyzed and found to be approximately 20 mum, being in a range predicted by theory. Thus, the wave initiation depends on the critical radius in an all-or-none fashion. For waves having high positive curvature of wave fronts, a linear relationship between the curvature and their normal velocity was established, allowing computation of a diffusion coefficient of 1.9 x 10(-5) cm(2)/s for the autocatalytic species, which agrees well with results previously obtained for negatively curved wave fronts. The analysis of the dispersion of wave velocity yielded the decrease of wave velocity for small initiation periods as predicted theoretically.
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Markus M, Hess B. Transitions between oscillatory modes in a glycolytic model system. Proc Natl Acad Sci U S A 2010; 81:4394-8. [PMID: 16593488 PMCID: PMC345596 DOI: 10.1073/pnas.81.14.4394] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A glycolytic model system consisting of the enzymes phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) is analyzed when subject to periodic substrate addition. The calculations are performed by using detailed rate laws that have been derived for the enzymes of Escherichia coli. Due to linear relationships between the metabolite concentrations, the numerical solutions can be displayed inside a trapezium, so that the concentrations of four different metabolites are indicated along the trapezium edges. The analysis reveals a rich variety of time patterns, corresponding to different periodic, quasiperiodic, and chaotic attractors. These patterns undergo complex hysteresis loops when bifurcation parameters are slowly changed-for example, by modulating the input amplitude. By using this technique up to four attractors coexisting in phase space are found. The time patterns corresponding to coexisting attractors can be switched into one another by triggering the system with short substrate pulses. Furthermore, conditions exist at which the triggering is autonomous-i.e., self-sustained (intermittent) switchings occur. The time between these switchings can be set externally by the value of the input amplitude. For conditions in which the periods of the oscillations are in the order of minutes, the self-sustained switching-which modulates these oscillations-can be in the order of hours.
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Kleinschmidt C, Hess B. Influence of an electrical potential on the charge transfer kinetics of bacteriorhodopsin. Biophys J 2010; 58:653-63. [PMID: 19431767 DOI: 10.1016/s0006-3495(90)82408-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The adsorption of bacteriorhodopsin(bR)-containing purple membranes (PM) to black lipid membranes (BLM) was used to study the charge translocation kinetics of bR upon flash excitation.The discharge of the PM-BLM system after charging upon illumination is found to proceed quite slowly (discharge time up to several minutes) but is considerably accelerated by addition of the protonophore FCCP.Therefore, the dependence of the proton transfer kinetics in bR on electrical potentials generated by preceding flashes of varying repetition rate and intensity was investigated. The kinetics are slowed down with increasing flash intensity as well as repetition rate. This effect is partly abolished by small amounts of FCCP.A new model is introduced which takes into account the instantaneous feedback of the electrical potential on the kinetics of the pump current. It explains the observed deviations from first-order kinetics and renders an approach with "distributed kinetics" unnecessary.
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Hess B, Chance B, Betz A. Isolierung eines oszillierenden Systems aus S. Carlsbergensis. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bbpc.19640680823] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Stueber D, Yu TY, Hess B, Kremer K, O'Connor RD, Schaefer J. Chain packing in polycarbonate glasses. J Chem Phys 2010; 132:104901. [PMID: 20232984 DOI: 10.1063/1.3330412] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Chain packing in homogeneous blends of carbonate (13)C-labeled bisphenol A polycarbonate with either (i) CF(3)-labeled bisphenol A polycarbonate or (ii) ring-F-labeled bisphenol A polycarbonate has been characterized using (13)C{(19)F} rotational-echo double-resonance (REDOR) nuclear magnetic resonance. In both blends, the (13)C observed spin was at high concentration, and the (19)F dephasing or probe spin was at low concentration. In this situation, an analysis in terms of a distribution of isolated heteronuclear pairs of spins is valid. Nearest-neighbor separation of (13)C and (19)F labels was determined by accurately mapping the initial dipolar evolution using a shifted-pulse version of REDOR. Based on the results of this experiment, the average distance from a ring-fluorine to the nearest (13)C=O is more than 1.2 A greater than the corresponding CF(3)-(13)C=O distance. Next-nearest and more-distant-neighbor separations of labels were measured in a 416-rotor-cycle constant-time version of REDOR for both blends. Statistically significant local order was established for the nearest-neighbor labels in the methyl-labeled blend. These interchain packing results are in qualitative agreement with predictions based on coarse-grained simulations of a specially adapted model for bisphenol A polycarbonate. The model itself has been previously used to determine static and dynamic properties of polycarbonate with results in good agreement with those from rheological and neutron scattering experiments.
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Bjelkmar P, Larsson P, Cuendet MA, Hess B, Lindahl E. Implementation of the CHARMM Force Field in GROMACS: Analysis of Protein Stability Effects from Correction Maps, Virtual Interaction Sites, and Water Models. J Chem Theory Comput 2010; 6:459-66. [PMID: 26617301 DOI: 10.1021/ct900549r] [Citation(s) in RCA: 728] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CHARMM27 is a widespread and popular force field for biomolecular simulation, and several recent algorithms such as implicit solvent models have been developed specifically for it. We have here implemented the CHARMM force field and all necessary extended functional forms in the GROMACS molecular simulation package, to make CHARMM-specific features available and to test them in combination with techniques for extended time steps, to make all major force fields available for comparison studies in GROMACS, and to test various solvent model optimizations, in particular the effect of Lennard-Jones interactions on hydrogens. The implementation has full support both for CHARMM-specific features such as multiple potentials over the same dihedral angle and the grid-based energy correction map on the ϕ, ψ protein backbone dihedrals, as well as all GROMACS features such as virtual hydrogen interaction sites that enable 5 fs time steps. The medium-to-long time effects of both the correction maps and virtual sites have been tested by performing a series of 100 ns simulations using different models for water representation, including comparisons between CHARMM and traditional TIP3P. Including the correction maps improves sampling of near native-state conformations in our systems, and to some extent it is even able to refine distorted protein conformations. Finally, we show that this accuracy is largely maintained with a new implicit solvent implementation that works with virtual interaction sites, which enables performance in excess of 250 ns/day for a 900-atom protein on a quad-core desktop computer.
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Schwaiger CS, Bjelkmar P, Hess B, Lindahl E. Structural Transition from Alpha- to 3_10-Helix Reduces the Free Energy Required for S4 Translation in Kv1.2/2.1 Voltage Sensors, and F233 Appears to Responsible for the Gating Barrier. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.2827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Finking G, Hess B, Hanke H. The value of phytoestrogens as a possible therapeutic option in postmenopausal women with coronary heart disease. J OBSTET GYNAECOL 2009; 19:455-9. [PMID: 15512363 DOI: 10.1080/01443619964184] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Large epidemiological studies have proved that the risk of coronary heart disease in postmenopausal women can be decreased by oestrogen replacement therapy. The effect is triggered by metabolic processes in the liver (decrease of LDL-cholesterol, increase of HDL-cholesterol) as well as by direct impact on the arterial wall (anti-oxidation, relaxation, anti-proliferation). The therapeutical usage of oestrogens is limited by an increased incidence of breast and endometrial cancer. Cyclic application of progestogens virtually eliminates the risk. Unfortunately, progestogens may antagonise the atheroprotective effect of oestrogens. Structurally modified oestrogens as well as selective oestrogen receptor modulators were investigated in clinical trials. They might provide the desired atheroprotective effects of oestrogen without negative side effects on the mammary gland or the endometrium. In this respect isoflavones also known as phytoestrogens, were analysed. They are widespread and occur naturally in many plants, especially in soy products. Cell culture and animal experiments as well as clinical studies revealed that phytoestrogens such as genistein and daidzein act atheroprotectively in the same way as oestrogen. Effects on the mammary gland or the endometrium could not be detected, but positive side effects on the bone metabolism and the decrease of certain types of cancer could be observed. In total, the therapeutical application of phytoestrogens in postmenopausal women seems to be of real and great benefit. We conclude that in women the risk of death from coronary heart disease increases after the onset of menopause. Recently discovered properties of phyto-oestrogens seem to be of great benefit as they do not seem to have any side effects on the mammary gland and the endometrium which are limiting factors for oestrogen replacement therapy.
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