V. A Parsegian | University of Massachusetts Amherst (original) (raw)
Papers by V. A Parsegian
Reviews of Modern Physics, 2010
ABSTRACT We formulate low-frequency charge-fluctuation forces between charged cylinders parallel ... more ABSTRACT We formulate low-frequency charge-fluctuation forces between charged cylinders parallel or skewed in salt solution: forces from dipolar van der Waals fluctuations and those from the correlated monopolar fluctuations of mobile ions. At high salt concentrations forces are exponentially screened. In low-salt solutions dipolar energies go as R −5 or R −4; monopolar energies vary as R −1 or ln R, where R is the minimal separation between cylinders. However, pairwise summability of rod-rod forces is easily violated in low-salt conditions. Perhaps the most important result is not the derivation of pair potentials but rather the demonstration that some of these expressions may not be used for the very problems that originally motivated their derivation.
Ciba Foundation symposium, 1984
'Fusion' in model systems usually refers to the decay of membrane configurations ... more 'Fusion' in model systems usually refers to the decay of membrane configurations that are inherently unstable because of the method of preparation. Natural fusion is a controlled event during which the underlying forces and instabilities are subject to the additional effects of biochemical reactions. To understand biological fusion one must be able first to assess the interplay among these physical and chemical factors. This paper reviews traditional measurements of electrostatic double layer and electrodynamic van der Waals forces acting between bilayer membranes. It also describes the much stronger hydration forces that have now been systematically studied. An essential part of any fusion event is the ability of membrane surfaces to overcome or circumvent the hydration barrier in order to make contact. This may be accomplished through applied force, through bridging substances that displace water from the membrane surface, or through biochemical modification of surfaces. In model systems, destruction of the hydration layer can cause violent adhesion, membrane deformation, and rupture. Natural fusion proceeds by more subtle processes whereby interfacial forces are harnessed in ways not yet understood.
Methods in enzymology, 1995
... [3] Macromolecules and Water: Probing with Osmotic S tress By V. ADRIAN PARSEGIAN, R.PETER RA... more ... [3] Macromolecules and Water: Probing with Osmotic S tress By V. ADRIAN PARSEGIAN, R.PETER RAND, and ... have begun to use osmotic stress on systems as varied as colloidal suspensions, microemul-sions, lipid-water liquid-crystals, heme proteins, and much else. ...
Proceedings of the National Academy of Sciences of the United States of America, Jan 4, 1994
We report direct measurements of force vs. separation between self-assembled proteins. These forc... more We report direct measurements of force vs. separation between self-assembled proteins. These forces are observed between collagen triple helices in native and reconstituted fibers. They are a combination of a short-range repulsion, which varies exponentially over at least five decay lengths, and an inferred, longer-ranged attraction responsible for spontaneous assembly. From 5 degrees C to 35 degrees C the relative contribution of the attraction to the net force increases with temperature. These forces are strikingly similar to the "hydration" forces measured between several other linear macromolecules (DNA, polysaccharides) and between lipid bilayer membranes. The decay length of the repulsive force agrees well with a theoretical estimate based on axial periodicity of the triple helix, suggesting another connection between molecular architecture and protein-protein interaction.
Biophysical journal, 1982
Lateral compressibilities of bilayers in multilayer lattices are given for 10 phospholipid prepar... more Lateral compressibilities of bilayers in multilayer lattices are given for 10 phospholipid preparation:dilauryl-, dimyristoyl-, dipalmitoyl-, distearoyl-, and dioleoylphosphatidylcholine (PC); egg phosphatidylethanolamine (PE); as well as cholesterol-containing bilayers of dipalmitoyl PC or of egg PC. Bilayer deformability is highly nonlinear and does not permit description in terms of a simple modulus. The presence of cholesterol or C=C bonds (dioleoyl PC) increases deformability, but freezing of acyl chains does not cause dramatic stiffening of the bilayer. Lateral compression of dilauryl PC an dimyristoyl PC causes a transition from "melted" to "frozen" acyl chains above the normal transition temperatures. Our measurements do not correspond in any obvious way to lateral compressibilities in monolayers at the air-water interface.
Biophysical journal, 1982
We have obtained force vs. separation relations between bilayers in 10 different phospholipid pre... more We have obtained force vs. separation relations between bilayers in 10 different phospholipid preparations: dilauroyl-dimyristoyl-, dipalmitoyl-, distearoyl-, or dioleoylphosphatidylcholine (PC); egg phosphatidylethanolamine; cholesterol-containing bilayers of dipalmitoyl PC and of egg PC. The chemical potential of water in the multilamellar lattice is determined at all water contents and changes continuously with bilayer separation; no discrete classes of water are observed. The interbilayer van der Waals force is estimated from the balance of forces at the bilayer separation where the multilayer lattice is in equilibrium with pure water. Although quantitative differences are evident for different phospholipids, all force curves but one show a clear, exponentially decaying "hydration "repulsion" whose decay distance is 2-3 A . Estimates of forces between bilayer vesicles show great sensitivity to the identity of the phospholipid polar group and to the packing of the ...
Annual review of biophysics and bioengineering, 1973
Methods in enzymology, 1986
The Journal of Physical Chemistry B, 2009
Proceedings of the National Academy of Sciences, 2000
There has been much confusion recently about the relative merits of different approaches, osmotic... more There has been much confusion recently about the relative merits of different approaches, osmotic stress, preferential interaction, and crowding, to describe the indirect effect of solutes on macromolecular conformations and reactions. To strengthen all interpretations of measurements and to forestall further unnecessary conceptual or linguistic confusion, we show here how the different perspectives all can be reconciled. Our approach is through the Gibbs-Duhem relation, the universal constraint on the number of ways it is possible to change the temperature, pressure, and chemical potentials of the several components in any thermodynamically defined system. From this general Gibbs-Duhem equation, it is possible to see the equivalence of the different perspectives and even to show the precise identity of the more specialized equations that the different approaches use.
Proceedings of the National Academy of Sciences, 1979
Proceedings of the National Academy of Sciences, 1994
Proceedings of the National Academy of Sciences, 2010
Langmuir, 1993
Interaction forces between dihexadecyldmethylammonium acetate (DHDAA) bilayers were measured usin... more Interaction forces between dihexadecyldmethylammonium acetate (DHDAA) bilayers were measured using oemotic streas (OS) and surface forces apparatus@ FA) techniques as a function of temperature and sodium acetate concentration (5-600 mM). Below T,, the ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2010
A complete form of the van der Waals dispersion interaction between an infinitely long anisotropi... more A complete form of the van der Waals dispersion interaction between an infinitely long anisotropic semiconducting/insulating thin cylinder and an anisotropic half space is derived for all separations between the cylinder and the half space. The derivation proceeds from the theory of dispersion interactions between two anisotropic infinite half spaces as formulated in Phys. Rev. A 71, 042102 (2005). The approach is valid in the retarded as well as nonretarded regimes of the interaction and is coupled with the recently evaluated ab initio dielectric response functions of various semiconducting/insulating single wall carbon nanotubes, enables the authors to evaluate the strength of the van der Waals dispersion interaction for all orientation angles and separations between a thin cylindrical nanotube and the half space. The possibility of repulsive and/or nonmonotonic dispersion interactions is examined in detail.
The Journal of Prosthetic Dentistry, 1983
The Journal of Chemical Physics, 2006
Reviews of Modern Physics, 2010
ABSTRACT We formulate low-frequency charge-fluctuation forces between charged cylinders parallel ... more ABSTRACT We formulate low-frequency charge-fluctuation forces between charged cylinders parallel or skewed in salt solution: forces from dipolar van der Waals fluctuations and those from the correlated monopolar fluctuations of mobile ions. At high salt concentrations forces are exponentially screened. In low-salt solutions dipolar energies go as R −5 or R −4; monopolar energies vary as R −1 or ln R, where R is the minimal separation between cylinders. However, pairwise summability of rod-rod forces is easily violated in low-salt conditions. Perhaps the most important result is not the derivation of pair potentials but rather the demonstration that some of these expressions may not be used for the very problems that originally motivated their derivation.
Ciba Foundation symposium, 1984
'Fusion' in model systems usually refers to the decay of membrane configurations ... more 'Fusion' in model systems usually refers to the decay of membrane configurations that are inherently unstable because of the method of preparation. Natural fusion is a controlled event during which the underlying forces and instabilities are subject to the additional effects of biochemical reactions. To understand biological fusion one must be able first to assess the interplay among these physical and chemical factors. This paper reviews traditional measurements of electrostatic double layer and electrodynamic van der Waals forces acting between bilayer membranes. It also describes the much stronger hydration forces that have now been systematically studied. An essential part of any fusion event is the ability of membrane surfaces to overcome or circumvent the hydration barrier in order to make contact. This may be accomplished through applied force, through bridging substances that displace water from the membrane surface, or through biochemical modification of surfaces. In model systems, destruction of the hydration layer can cause violent adhesion, membrane deformation, and rupture. Natural fusion proceeds by more subtle processes whereby interfacial forces are harnessed in ways not yet understood.
Methods in enzymology, 1995
... [3] Macromolecules and Water: Probing with Osmotic S tress By V. ADRIAN PARSEGIAN, R.PETER RA... more ... [3] Macromolecules and Water: Probing with Osmotic S tress By V. ADRIAN PARSEGIAN, R.PETER RAND, and ... have begun to use osmotic stress on systems as varied as colloidal suspensions, microemul-sions, lipid-water liquid-crystals, heme proteins, and much else. ...
Proceedings of the National Academy of Sciences of the United States of America, Jan 4, 1994
We report direct measurements of force vs. separation between self-assembled proteins. These forc... more We report direct measurements of force vs. separation between self-assembled proteins. These forces are observed between collagen triple helices in native and reconstituted fibers. They are a combination of a short-range repulsion, which varies exponentially over at least five decay lengths, and an inferred, longer-ranged attraction responsible for spontaneous assembly. From 5 degrees C to 35 degrees C the relative contribution of the attraction to the net force increases with temperature. These forces are strikingly similar to the "hydration" forces measured between several other linear macromolecules (DNA, polysaccharides) and between lipid bilayer membranes. The decay length of the repulsive force agrees well with a theoretical estimate based on axial periodicity of the triple helix, suggesting another connection between molecular architecture and protein-protein interaction.
Biophysical journal, 1982
Lateral compressibilities of bilayers in multilayer lattices are given for 10 phospholipid prepar... more Lateral compressibilities of bilayers in multilayer lattices are given for 10 phospholipid preparation:dilauryl-, dimyristoyl-, dipalmitoyl-, distearoyl-, and dioleoylphosphatidylcholine (PC); egg phosphatidylethanolamine (PE); as well as cholesterol-containing bilayers of dipalmitoyl PC or of egg PC. Bilayer deformability is highly nonlinear and does not permit description in terms of a simple modulus. The presence of cholesterol or C=C bonds (dioleoyl PC) increases deformability, but freezing of acyl chains does not cause dramatic stiffening of the bilayer. Lateral compression of dilauryl PC an dimyristoyl PC causes a transition from "melted" to "frozen" acyl chains above the normal transition temperatures. Our measurements do not correspond in any obvious way to lateral compressibilities in monolayers at the air-water interface.
Biophysical journal, 1982
We have obtained force vs. separation relations between bilayers in 10 different phospholipid pre... more We have obtained force vs. separation relations between bilayers in 10 different phospholipid preparations: dilauroyl-dimyristoyl-, dipalmitoyl-, distearoyl-, or dioleoylphosphatidylcholine (PC); egg phosphatidylethanolamine; cholesterol-containing bilayers of dipalmitoyl PC and of egg PC. The chemical potential of water in the multilamellar lattice is determined at all water contents and changes continuously with bilayer separation; no discrete classes of water are observed. The interbilayer van der Waals force is estimated from the balance of forces at the bilayer separation where the multilayer lattice is in equilibrium with pure water. Although quantitative differences are evident for different phospholipids, all force curves but one show a clear, exponentially decaying "hydration "repulsion" whose decay distance is 2-3 A . Estimates of forces between bilayer vesicles show great sensitivity to the identity of the phospholipid polar group and to the packing of the ...
Annual review of biophysics and bioengineering, 1973
Methods in enzymology, 1986
The Journal of Physical Chemistry B, 2009
Proceedings of the National Academy of Sciences, 2000
There has been much confusion recently about the relative merits of different approaches, osmotic... more There has been much confusion recently about the relative merits of different approaches, osmotic stress, preferential interaction, and crowding, to describe the indirect effect of solutes on macromolecular conformations and reactions. To strengthen all interpretations of measurements and to forestall further unnecessary conceptual or linguistic confusion, we show here how the different perspectives all can be reconciled. Our approach is through the Gibbs-Duhem relation, the universal constraint on the number of ways it is possible to change the temperature, pressure, and chemical potentials of the several components in any thermodynamically defined system. From this general Gibbs-Duhem equation, it is possible to see the equivalence of the different perspectives and even to show the precise identity of the more specialized equations that the different approaches use.
Proceedings of the National Academy of Sciences, 1979
Proceedings of the National Academy of Sciences, 1994
Proceedings of the National Academy of Sciences, 2010
Langmuir, 1993
Interaction forces between dihexadecyldmethylammonium acetate (DHDAA) bilayers were measured usin... more Interaction forces between dihexadecyldmethylammonium acetate (DHDAA) bilayers were measured using oemotic streas (OS) and surface forces apparatus@ FA) techniques as a function of temperature and sodium acetate concentration (5-600 mM). Below T,, the ...
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2010
A complete form of the van der Waals dispersion interaction between an infinitely long anisotropi... more A complete form of the van der Waals dispersion interaction between an infinitely long anisotropic semiconducting/insulating thin cylinder and an anisotropic half space is derived for all separations between the cylinder and the half space. The derivation proceeds from the theory of dispersion interactions between two anisotropic infinite half spaces as formulated in Phys. Rev. A 71, 042102 (2005). The approach is valid in the retarded as well as nonretarded regimes of the interaction and is coupled with the recently evaluated ab initio dielectric response functions of various semiconducting/insulating single wall carbon nanotubes, enables the authors to evaluate the strength of the van der Waals dispersion interaction for all orientation angles and separations between a thin cylindrical nanotube and the half space. The possibility of repulsive and/or nonmonotonic dispersion interactions is examined in detail.
The Journal of Prosthetic Dentistry, 1983
The Journal of Chemical Physics, 2006