THE ROLE OF LONG-RANGE FORCES IN THE STABILITY OF NEMATIC FILMS

2002 ◽  
pp. 297-297
Author(s):  
M. P. VALIGNAT ◽  
F. VANDENBROUCK ◽  
A. M. CAZABAT
Keyword(s):  
Long Range ◽  
The Stability

THE ROLE OF LONG-RANGE FORCES IN THE COHESION OF LIPOPROTEINS

1962 ◽  
Vol 40 (1) ◽  
pp. 1287-1298 ◽  
Author(s):  
L. Salem
Keyword(s):  
Long Range ◽  
Saturated Hydrocarbon ◽  
Dispersion Forces ◽  
Intermolecular Distance ◽  
Dispersion Energy ◽  
Hydrocarbon Chains ◽  
Energy Of Interaction ◽  
The Stability ◽  
Electronic Ground

The various long-range forces which are effective between molecules in their electronic ground states are examined. Orders of magnitude are given for those forces which should occur in the interaction of lipide and protein chains. It is found that electrostatic forces should be responsible for bringing and holding together protein and lipide components, but London – Van der Waals dispersion forces are probably of paramount importance in maintaining the lipide chains together in micelles or double layers.Special attention is drawn to the dispersion forces and to the conditions under which these forces are locally additive; one can calculate accurate values of the dispersion energy of interaction between saturated hydrocarbon chains at short distances (a few angstroms apart) by adding all the bond–bond interactions. A general expression is given for the dispersion energy between two parallel and opposed chains built out of identical units, and numerical values are given for the case of closely packed hydrocarbon chains.The total attraction energy is extremely sensitive to the intermolecular distance. The role of this "distance-specificity" in interactions involving unsaturated fatty acid chains and its contribution to the stability of lipoproteins is briefly examined.

THE ROLE OF LONG-RANGE FORCES IN THE COHESION OF LIPOPROTEINS

1962 ◽  
Vol 40 (9) ◽  
pp. 1287-1298 ◽  
Author(s):  
L. Salem
Keyword(s):  
Long Range ◽  
Saturated Hydrocarbon ◽  
Dispersion Forces ◽  
Intermolecular Distance ◽  
Dispersion Energy ◽  
Hydrocarbon Chains ◽  
Energy Of Interaction ◽  
The Stability ◽  
Electronic Ground

The various long-range forces which are effective between molecules in their electronic ground states are examined. Orders of magnitude are given for those forces which should occur in the interaction of lipide and protein chains. It is found that electrostatic forces should be responsible for bringing and holding together protein and lipide components, but London – Van der Waals dispersion forces are probably of paramount importance in maintaining the lipide chains together in micelles or double layers.Special attention is drawn to the dispersion forces and to the conditions under which these forces are locally additive; one can calculate accurate values of the dispersion energy of interaction between saturated hydrocarbon chains at short distances (a few angstroms apart) by adding all the bond–bond interactions. A general expression is given for the dispersion energy between two parallel and opposed chains built out of identical units, and numerical values are given for the case of closely packed hydrocarbon chains.The total attraction energy is extremely sensitive to the intermolecular distance. The role of this "distance-specificity" in interactions involving unsaturated fatty acid chains and its contribution to the stability of lipoproteins is briefly examined.

scholarly journals Role of long-range aromatic clique and community in protein stability

2018 ◽  
Author(s):  
P Mahanta ◽  
A Bhardwaj ◽  
VS Reddy ◽  
S Ramakumar
Keyword(s):  
Protein Stability ◽  
Long Range ◽  
Triosephosphate Isomerase ◽  
Solvent Accessible Surface Area ◽  
Aromatic Residues ◽  
Aromatic Interactions ◽  
The Stability ◽  
Gh10 Xylanase ◽  
Aromatic Interaction

AbstractAromatic interactions make an important contribution to protein structure, function, folding and have attracted intense study. Earlier studies on a recombinant xylanase from Bacillus sp. NG-27 (RBSX), which has the ubiquitous (beta/alpha)8-triosephosphate isomerase barrel fold showed that three aromatic residues to alanine substitutions, in the N-terminal and C-terminal regions, significantly decreased the stability of the enzyme. Of these mutations, F4A mutation decreased the stability of the enzyme by ∼4 degree C, whereas W6A mutation and Y343A mutation remarkably decreased the stability of the enzyme by ∼10 degree C. On the other hand, the F4W mutation did not affect the thermal stability of RBSX. We provide here a network perspective of aromatic-aromatic interactions in terms of aromatic clique community and long-range association. Our study reveals that disruption of long-range k-clique aromatic interaction cluster holding the N- and C-terminal regions are associated with the decreased stability of the enzyme. The present work reiterates as well as expands on those findings concerning the role of interactions between the N- and C-terminus in protein stability. Furthermore, comparative analyses of crystal structures of homologous pairs of proteins from thermophilic and mesophilic organisms emphasize the prevalence of long-range k-clique communities of aromatic interaction that may be playing an important role and highlights an additional source of stability in thermophilic proteins. The design principle based on clustering of long-range aromatic residues in the form of aromatic-clique and clique community may be effectively applied to enhance the stability of enzymes for biotechnological applications.DatabaseThe coordinates o fF4A, F4W, W6A, and Y343A are deposited in the PDB database under the accession numbers 5EFF, 5E58, 5EFD, and 5EBA respectively.AbbreviationsBSX, xylanase from Bacilllus sp. NG-27; RBSX, recombinant BSX xylanase; TIM, Triosephosphate isomerase; GH10, Glycosyl hydrolase family 10; 3D, three-dimensional; r.m.s.d, root mean square deviation; RSA, relative solvent accessible surface area; Tm, melting temperature; CD, Circular Dichroism; BHX, GH10 xylanase from Bacillus halodurans; BFX, GH10 xylanase from Bacillus firmus; TmxB, GH10 xylanase from Thermotoga maritima

The Role of Long Range Forces in the Stability of Nematic Films

2001 ◽  
Vol 358 (1) ◽  
pp. 287-299
Author(s):  
Marie-Pierre Valignat ◽  
Francois Vandenbrouck ◽  
Anne-Marie Cazabat
Keyword(s):  
Long Range ◽  
The Stability

The Role of Technological Change in the Long-run Global Economy Forecasting

2013 ◽  
pp. 97-116 ◽  
Author(s):  
A. Apokin
Keyword(s):  
Technological Change ◽  
Data Quality ◽  
Long Range ◽  
Global Economy ◽  
World Economy ◽  
Qualitative Approaches ◽  
Long Run ◽  
The World ◽  
National Economies

The author compares several quantitative and qualitative approaches to forecasting to find appropriate methods to incorporate technological change in long-range forecasts of the world economy. A?number of long-run forecasts (with horizons over 10 years) for the world economy and national economies is reviewed to outline advantages and drawbacks for different ways to account for technological change. Various approaches based on their sensitivity to data quality and robustness to model misspecifications are compared and recommendations are offered on the choice of appropriate technique in long-run forecasts of the world economy in the presence of technological change.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

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