Abstract:
:Conductance noise measurement of the open states of alamethicin transmembrane channels reveals excess noise attributable to cooperative low-frequency molecular dynamics that can generate fluctuations approximately 1 A rms in the effective channel pore radius. Single-channel currents through both persistent and nonpersistent channels with multiple conductance states formed by purified polypeptide alamethicin in artificial phospholipid bilayers isolated onto micropipettes with gigaohm seals were recorded using a voltage-clamp technique with low background noise (rms noise < 3 pA up to 20 kHz). Current noise power spectra between 100 Hz and 20 kHz of each open channel state showed little frequency dependence. Noise from undetected conductance state transitions was insignificant. Johnson and shot noises were evaluated. Current noise caused by electrolyte concentration fluctuation via diffusion was isolated by its dependence on buffer concentration. After removing these contributions, significant current noise remains in all persistent channel states and increases in higher conductance states. In nonpersistent channels, remaining noise occurs primarily in the lowest two states. These fluctuations of channel conductance are attributed to thermal oscillations of the channel molecular conformation and are modeled as a Langevin translational oscillation of alamethicin molecules moving radially from the channel pore, damped mostly by lipid bilayer viscosity.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Mak DO,Webb WWdoi
10.1016/S0006-3495(95)80103-7subject
Has Abstractpub_date
1995-12-01 00:00:00pages
2337-49issue
6eissn
0006-3495issn
1542-0086pii
S0006-3495(95)80103-7journal_volume
69pub_type
杂志文章abstract::The shape distributions of normal and hardened human and rabbit erythrocytes and platelets were obtained for edge-on orientations of a few hundred freely rotating cells from analyses of microphotographs obtained similarly as by Ponder(1930, Q. J. Exp. Physiol. 20:29) by phase-contrast microscopy at 800 X magnification...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(76)85756-6
更新日期:1976-09-01 00:00:00
abstract::Viral infection begins with the binding of a virus to a specific target on the surface of the host cell, followed by viral genome delivery into the host and a continuation of the infection process. Before binding occurs, the virus must first find its receptor by a process whose details are largely unknown. We applied ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.05.014
更新日期:2011-06-22 00:00:00
abstract::The processes of cell growth and budding of the yeast cells Saccharomyces cerevisiae, which were gently immobilized on 3% agar and submerged in culture medium, were successfully imaged with an atomic force microscope for 6-7 h. Similar experiments on chemically fixed cells did not detect any appreciable change in thei...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(95)80147-5
更新日期:1995-12-01 00:00:00
abstract::A previously established multiscale population genetics model posits that fitness can be inferred from the physical properties of proteins under the physiological assumption that a loss of stability by any protein confers the lethal phenotype to an organism. Here, we develop this model further by positing that replica...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2009.11.048
更新日期:2010-04-07 00:00:00
abstract::Sedimentation velocity analytical ultracentrifugation is an important tool in the characterization of macromolecules and nanoparticles in solution. The sedimentation coefficient distribution c(s) of Lamm equation solutions is based on the approximation of a single, weight-average frictional coefficient of all particle...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.106.081372
更新日期:2006-06-15 00:00:00
abstract::Previous studies on aurein 2.2 and 2.3 in DMPC/DMPG and POPC/POPG membranes have shown that bilayer thickness and phosphatidylglycerol content have a significant impact on the interaction of these peptides with membrane bilayers. Further examination with the DiSC(3)5 assay has indicated that aurein 2.2 induces greater...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2010.08.077
更新日期:2010-11-03 00:00:00
abstract::Previously, we discussed the calculation of the dipole moments of small proteins using the three-dimensional protein data-base. Our results demonstrate that the calculated dipole moments are in acceptable agreement with measured values. We, however, noted the difficulty of the calculation with larger proteins, in part...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(93)81524-8
更新日期:1993-05-01 00:00:00
abstract::The stability of OmpA in large unilamellar vesicles of dilauroyl phosphatidylcholine was studied using different concentrations of urea. The effective energy of unfolding, as determined from refolding experiments, is greater than that for small sonicated unilamellar vesicles by an amount that is compatible with estima...
journal_title:Biophysical journal
pub_type: 信件
doi:10.1529/biophysj.106.091439
更新日期:2006-10-15 00:00:00
abstract::Aerotaxis is a particular form of "energy taxis". It is based on a largely elusive signal transduction machinery. In aerotaxis, oxygen dissolved in water plays the role of both attractant (at moderate concentrations) and repellent (at high and low concentrations). Cells swimming from favorable oxygen concentrations in...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74775-4
更新日期:2003-12-01 00:00:00
abstract::Extraction from simulations of the area compressibility moduli of the monolayers in a bilayer is considered theoretically. A statistical mechanical derivation shows that the bilayer modulus is the sum of the two monolayer moduli, as is often supposed but contrary to a recent study. Seemingly plausible assumptions rega...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2019.08.016
更新日期:2019-09-17 00:00:00
abstract::Protein-mediated membrane remodeling is a ubiquitous and critical process for proper cellular function. Inverse Bin/Amphiphysin/Rvs (I-BAR) domains drive local membrane deformation as a precursor to large-scale membrane remodeling. We employ a multiscale approach to provide the molecular mechanism of unusual I-BAR dom...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2019.06.025
更新日期:2019-08-06 00:00:00
abstract::The type 2a sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA2a) plays a key role in intracellular Ca2+ regulation in the heart. We have previously shown evidence of stable homodimers of SERCA2a in heterologous cells and cardiomyocytes. However, the functional significance of the pump dimerization remains unclear. H...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2020.08.025
更新日期:2020-10-06 00:00:00
abstract::The stoichiometric matrix, S, represents a mapping of reaction rate vectors into a space of concentration time derivatives. The left null space of the stoichiometric matrix contains the dynamic invariants: a combination of concentration variables, referred to as metabolic pools, whose total concentration does not chan...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(03)74450-6
更新日期:2003-07-01 00:00:00
abstract::The earliest event in exocytosis is the formation of a fusion pore, an aqueous channel that connects the lumen of a secretory granule with the extracellular space. We can observe the formation of individual fusion pores and their subsequent dilation or closure by measuring the changes in the admittance of patch-clampe...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(92)81884-2
更新日期:1992-03-01 00:00:00
abstract::The effects of the anionic tungsten carbonyl complex [W(CO)(5)SC(6)H(5)](-) and its fluorinated analog [W(CO)(5)SC(6)F(5)](-) on the electrical properties of the plasma membrane of mouse myeloma cells were studied by the single-cell electrorotation technique. At micromolar concentrations, both compounds gave rise to a...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(00)76400-9
更新日期:2000-09-01 00:00:00
abstract::Chiral objects which scatter and absorb preferentially left versus right circularly polarized light give rise to bright-field circular dichroism (CD) images containing contributions from both these two phenomena. These contributions are separated and characterized mathematically, and the effect of the dimensions of th...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(91)82334-7
更新日期:1991-06-01 00:00:00
abstract::G-protein-coupled receptors (GPCRs) are important membrane proteins that mediate cellular signaling and represent primary targets for about one-third of currently marketed drugs. Recent x-ray crystallographic studies identified distinct conformations of GPCRs in the active and inactive states. An allosteric sodium ion...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2015.03.003
更新日期:2015-04-07 00:00:00
abstract::Kinetic measurements of the self-assembly of proteins into amyloid fibrils are often used to make inferences about molecular mechanisms. In particular, the lag time--the quiescent period before aggregates are detected--is often found to scale with the protein concentration as a power law, whose exponent has been used ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2014.11.3465
更新日期:2015-02-03 00:00:00
abstract::Although the majority of free cellular cholesterol is present in the plasma membrane, cholesterol homeostasis is principally regulated through sterol-sensing proteins that reside in the cholesterol-poor endoplasmic reticulum (ER). In response to acute cholesterol loading or depletion, there is rapid equilibration betw...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.08.042
更新日期:2013-10-15 00:00:00
abstract::The adsorption of hydrophobic ions such as tetraphenylborate to thin lipid membranes is known to saturate at approximately 0.1 ion/(nm)2. This saturation can be quantitatively explained by electrostatic repulsion between the ions if they are treated as discrete, mobile particles that adsorb within the lipid at least p...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(82)84489-5
更新日期:1982-07-01 00:00:00
abstract::The plasma membrane of cells has a complex architecture based on the bidimensional liquid-crystalline bilayer arrangement of phospho- and sphingolipids, which in turn embeds several proteins and is connected to the cytoskeleton. Several studies highlight the spatial membrane organization into more ordered (Lo or lipid...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2018.11.3141
更新日期:2019-02-05 00:00:00
abstract::Molecular dynamics simulations have been applied to the DNA octamer d(GCGCA-GAAC). d(GTTCGCGC), which has an adenine bulge at the center to determine the pathway for interconversion between the stacked and extended forms. These forms are known to be important in the molecular recognition of bulges. From a total of ~35...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(01)75705-0
更新日期:2001-07-01 00:00:00
abstract::Current viral docking models have relied upon the assumption that bond formation and breakage are independent of viral and docking surface geometry, as well as the forces exerted on the bonds. This assumption, known as the equivalent site hypothesis (ESH), is examined in detail using a newly developed simulation techn...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1529/biophysj.103.027813
更新日期:2004-06-01 00:00:00
abstract::The temporal dynamics of the concentrations of several proteins are tightly regulated, particularly for critical nodes in biological networks such as transcription factors. An important mechanism to control transcription factor levels is through autoregulatory feedback loops where the protein can bind its own promoter...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2011.08.005
更新日期:2011-09-21 00:00:00
abstract::This paper describes an analysis of microscopic models for the coupling between ion flow and rotation of bacterial flagella. In model I it is assumed that intersecting half-channels exist on the rotor and the stator and that the driving ion is constrained to move together with the intersection site. Model II is based ...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(88)83065-0
更新日期:1988-01-01 00:00:00
abstract::In a cell-populated collagen gel, intrinsic fiber structure visible in differential interference contrast images can provide markers for an in situ strain gauge to quantify cell-gel mechanics, while optical sections of fluorescent protein distribution capture cytoskeletal kinematics. Mechanics quantification can be de...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/s0006-3495(03)75077-2
更新日期:2003-04-01 00:00:00
abstract::Exposure of aqueous suspensions of fragments of the purple membrane of Halobacterium halobium to electric field pulses leads to transient linear dichroism phenomena. The effects are interpreted in terms of field-induced alignments of the bacteriorhodopsin chromophore. Two observed relaxation times (tau) are attributed...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/S0006-3495(77)85558-6
更新日期:1977-07-01 00:00:00
abstract::Collagen fibrils form extracellular networks that regulate cell functions and provide mechanical strength to tissues. Collagen fibrillogenesis is an entropy-driven process promoted by warming and reversed by cooling. Here, we investigate the influence of noncovalent interactions mediated by the collagen triple helix o...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2013.05.035
更新日期:2013-07-02 00:00:00
abstract::Toward quantitative description of protein aggregation, we develop a computationally efficient method to evaluate the potential of mean force between two folded protein molecules that allows for complete sampling of their mutual orientation. Our model is valid at moderate ionic strengths and accounts for the actual ch...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.03.025
更新日期:2012-04-18 00:00:00
abstract::Negatively charged phospholipids are an important component of biological membranes. The thermodynamic parameters governing self-assembly of anionic phospholipids are deduced here from isothermal titration calorimetry. Heats of demicellization were determined for dioctanoyl phosphatidylglycerol (PG) and phosphatidylse...
journal_title:Biophysical journal
pub_type: 杂志文章
doi:10.1016/j.bpj.2012.01.049
更新日期:2012-03-07 00:00:00